Intake & Exhaust

DC Sports Updates the TSX Header Design – Better Flex at Last!

Many 04-08 TSX owners are familiar with the DC Sports header, which is known to be a great bargain in terms of power-for-dollar. Also, it is one of the only available headers with a CARB Exemption Order number making it legal for street use in all 50 US States.

However many are also familiar with an issue with the flex joint failing over time (sometimes, in a very short time). These failures cause a noticeable and embarrassing leak and reduction in power.

Today we have some awesome news! DC Sports management has recognized the issue and developed new flex joints that hopefully will do away with this issue once and for all! Here we have a prototype of a DC Sports new design alongside a failed unit, to compare.

Old DC Sports AHC6016 for 04-08 TSX on the left, new on the right.
Outside the old flex looks fine…
Inside tells a different story.

We have been informed that the new flex shown in the images is the new standard design, which is significantly better than the outgoing version. But DC is not done working on this issue.

According to DC Sports, the demand on the flex is pretty intense causing the failures. In discussion, they told us “We are actively testing one now without the flex joint and one with a much higher quality flex joint. Once we have enough milage under real-world driving we will decide which is the better of the two options.”

We expect that they will choose an option that does retain flex since this is good for relieving stress on the pipes and helps prevent cracking as the exhaust moves with engine torque.

For now, you can buy a pipe with confidence that the flex issues of the past have been resolved! (Note the date of this posting relative to posts or search results from the past…anything older than 2021 in date is “old news.”)

Heeltoe Explains Intake & Exhaust

Types of Air Filters

The air filter’s primary function is to remove dirt and debris from the induction charge before entering the intake tract, and therefore, the engine. Keeping dirt out of the engine is a primary means of helping it last longer. If unfiltered air can enter the engine oil, dirt can cause premature wear of internal parts. Replacing or cleaning the air filter is an important part of regular vehicle maintenance, outlined in the vehicle owner’s manual.

This article outlines some of the many different kinds of filters. Cotton oiled, dry cotton, and foam filters are the most popular aftermarket performance filter media. Be aware of the different types, and that some that are universal, non-OE style filters that may need adapters to install properly (cone filters).

Panel versus Cone

Most factory air filter elements are flat panels that are sandwiched into a box in the intake tract (airbox). The box fasteners are removed, the box opened, and the filter panel lifted out. The factory filter is a specific shape with a gasket around the outer edge to seal the airbox lid. Aftermarket panel replacements are designed similarly to the factory panel in shape and size to fit the OE application but are made from different materials to change the air-flow characteristics.

Some original equipment and most aftermarket applications use a cone filter. Cone filters go over the end of an intake tube and attach to it with either a clamp or a flange. These open-element cone filters are typically used in place of a factory airbox, doing away with the potentially restrictive plumbing associated with them. Higher performance applications will almost always use an open-element cone filter. Please note that custom mounting may be required if not using these universal cone filters with a complete air intake system upgrade.

Factory Paper

Most factory filters are made of paper material. The factory air filters are not bad for performance and do last reasonably long. These filters cannot generally be cleaned and are replacement only. Some enthusiasts will claim a factory filter is the best for use on road cars, where there is a lot of debris and a long time in between service intervals. Many enthusiasts will replace the factory filter with aftermarket cotton or foam filters to increase the air-flow into the engine. The power gains are reported inconsistently, but it is considered common knowledge that replacing a factory filter with a higher flowing aftermarket one will help increase the power potential of the engine.

Cotton, Oiled

For more airflow, a popular upgrade is using cotton drop-in replacement filters. The cotton element is a more open matrix than the factory paper and lets more air through. With oiled cotton filters, a light-weight oil is applied to the element which provides a “sticky” place for dirt to attach to before it goes into the engine. The oil is effective in trapping dirt and must be cleaned periodically. These are permanent filters that can be cleaned and re-oiled with a kit from the manufacturer. Some owners have condemned the use of oiled filters because excess oil can be drawn through the filter into sensitive mass-air flow reading components, causing the engine to run poorly. Our stance is, be careful not to over-oil when servicing your oiled filter…it is easy to do this and then blame the filter for the problem, when in reality these filters are often very viable performance parts.

Cotton, Dry

Because of the growing stigma against oiled filters, and to reduce maintenance effort and cost, there is a newer style of cotton elements called dry filters. A dry filter replacement which flows more than stock like an oiled does, but without the oil. The matrix is tighter which allows the trapping of dirt, but the cotton still fundamentally flows more than paper. The cleaning is easier without needing to apply oil. Just wash with water, allow to dry, and reinstall.


Used in many racing applications, foam filters are known to flow a lot of air. We’ve heard reports of foam filters being the highest flowing available. These filters can be made with a foam of various porosity, or layers of foam with different density, with the more open elements using oil to help trap dirt. They are softer and more pliable making them useful in a wide variety of applications, such as wrapped over intake velocity stacks. Foam filters can often be cleaned, however foam filters are less durable than the factory paper or cotton filters, and may need replacement sooner if used and cleaned frequently. Many enthusiasts feel the power gains are a good trade-off for less durability compared to cotton filters.

Intake & Exhaust

ATLP, XLR8, and RV6 J-pipes tested together. PLUS ATLP V2-R debut!

With all the different J-Pipes available on the market for Honda/Acura V6 cars, Heeltoe always tries to get enough information to not only make better parts but also to make your buying decision easier. Few if any others have done real, honest back to back these of popular Acura J-pipes. Heeltoe is in your corner with real test info!

NOTICE as of 2018: The ATLP V2-R j-pipe was replaced with the ATLP V3-R j-pipe. The primary tubes on the V3-R were made shorter, similar to the V2. Also improved design has made the part a better fit on the 7th Generation (2003-07) Accord V6 as the V2-R had subframe contact on that car.

The test car was a boosted TL-S with a Flashpro and a high boost pulley. It was an automatic as well. If gains and losses are viewed as percentages we feel the relative graph data above will be indicative of what we would see on an NA J-series.

AFR and IAT were both monitored closely for consistency. No pipes required retuning to get these numbers, and tuning would not have needed noticeable differences (we played with it…it would not have). But the tune in the car was optimized when we got to it having just been dialed in on the same dyno the day before.

All tests done on the same day, same car, same dyno, same procedure:
3 pulls to heat up engine, then rest for 5 minutes, then one pull to be the one to use for the test. In all cases the “1 pull” was about on average with the rest of the pre-runs. We feel this data is all repeatable and reliable when done under the same conditions.

Full disclosure, at the time of testing and posting, ATLP is produced by Heeltoe. If anyone wants to call Church Testing to validate the test, feel free. Again, the raw data is available for whoever wants it.

Our takeaways:

  • Pay attention to the scale on dyno graphs. We posted no power figures to force you to look at the scale. The first two graphs are the same, but the scales are different.
  • 3″ cat-back piping makes a difference, no matter what j-pipe you have. ATLP is currently the only one on the market offering bolt-on options for it!
  • The original ATLP V2 gives up power when you are driving slow, but makes more power than anything else when you are driving quicker than…well, slow.
  • The XLR8 V2 is really similar to the V2-R. Pipe lengths are almost the same But we didn’t test it with a 3″ mid pipe to see if that makes much of a difference on an XLR8. Wish I would have!
  • RV6 vs XLR8 are here and there and back and forth…but the ATLP performs best on anything above your automatic’s torque converter lockup point.
  • The original ATLP V2 with a Race Pipe and our 3″ sections make for the option to get the most power. The larger piping adds to the gains and helps to recover some lost bottom-range torque.

In other news, the ATLP options were easier to install. RV6 fit great but awkward to install with the long floppy pipes. XLR8 was off a bit. It took more forcing on the cats and didn’t line up as well as the others on the cat-back.

They all sounded about the same. The 3″ makes the car sound like a monster though.

ATLP V2 vs XLR8 V2 vs RV6 V3

XLR8 V2 vs ATLP V2-R

All ATLP Shootout

We spent a lot of money and time to develop an ATLP version of the XLR8 pipe with a 3″ collector. And to learn that we still like the ATLP V2 best. It allows you to swap a stock cat back in unlike all the others, fits great, sounds great, makes great power…and is the least costly.

Intake & Exhaust Universal Fit Blogging

Import Tuner Power Pages Featuring ATLP Cat-Back for the Acura RDX

Import Tuner likes taking parts and slapping them on cars in a segment called Power Pages, displaying what power benefits they offer. We found a nice article showing some great gains with the ATLP cat-back for the RDX.

Honda Tuning RDX "Black Pearl"

Here is a link to the full article:

Among a Hondata Reflash and K&N Intake, gains were handily made with the addition of the ATLP Cat-Back.

Here is what they had to say:

Reducing exhaust backpressure is crucial to freeing up power in turbocharged cars. But, in vehicles like the RDX, so is maintaining a subtle appearance and sound. No one wants to outfit their $30K luxury crossover with a raspy “fart can”; that’s why the ATLP unit is an attractive addition. Mandrel-bent, 2.5-inch 439 stainless steel piping scavenges exhaust gas efficiently, resists corrosion and remains durable under high-heat duress, while proprietary heat resistant packing in straight-through silencers ensures years of quiet operation, and a polished 402 stainless muffler and dual four-inch tips give a more aggressive, yet mature finish.

Again, midrange and top-end power come at the cost of a few ponies down low, but with more than 10 whp and 11 lb-ft of torque throughout the powerband from below 4,500 rpm until redline, we consider this a non-issue.

I’m not sure I see where the power compromise is in their chart because it is such a small difference below 4000 rpm, but the midrange gains are undeniable:

Intake & Exhaust

3rd Gen Acura TL ATLP / XLR8 Exhaust Comparo Video

ATLP is a renowned brand in the Acura community for providing and exhaust with a look that is aggressive and timeless and a sound that is intoxicating without being overt. XLR8 is a staple of the Acura TL community as well, providing an exhaust that is crisp and clean looking but has the sound of a performance exotic. There are many videos online showing how each sound, but until now we know of no truly well-made video that compares the two back to back.

In this exclusive video, we bring the sounds of the ATLP and XLR8 Base and Quad systems to life in true HD sound, back to back on the same cars, for you to use to choose a system with confidence!

* Note, we have selected non-resonated systems for the sound test as the sounds will not be obviously changed with resonators, which are designed to reduce interior sound. Interior sound clips were taken but not used as they were nearly indiscernible from each other. The sound of both systems is apparent in both cars in normal driving, and the drone is minute. We realize drone and its impact on the livability of a system is a subjective balance. Heelote’s recommendation: If you want to hear the exhaust, don’t get a resonator. If you don’t want to hear it inside the car as much, get one. If you are not sure, don’t get one and weld one in later as needed.

Intake & Exhaust

J-Pipe Comparison Test Round 1: ATLP vs RV6 vs XLR8 * Results Inconclusive!

PLEASE NOTE: The results of this test were INCONCLUSIVE. Each successive pipe tested produced more power than the last, even when the first one was dynoed again last. Please read the entire posting and don’t make judgments based on the graphs alone. There is a much more accurate and informative test here: ATLP, XLR8, and RV6 J-pipes tested together. ATLP V2-R debut!

We just got back from Church Auto Testing, where we did another round of J-Pipe shootouts yesterday. Some may recall the last shootout we did involved only the RV6 V3 and ATLP V2 designs, and that the ATLP while showing favorable performance above 4000 RPM, gave up some torque to RV6 in the lower RPMs. The car tested was a Base model TL with a 3.2L engine and a manual trans.

Of course, we were also testing prototype revisions of the new ATLP V2R pipe which has been in the works.

Eager to get more data and urged on by the ever-anticipating Acurazine community, coupled with a relatively extraordinary dyno report on the XLR8 V2 pipe, we finally made our way back. The parts we brought with us this time were an ATLP V2 pipe with optional Race pipe cat delete, an RV6 V3 J-pipe, and an XLR8 V2 J-pipe (both of the latter with integrated cat-deletes as part of the design). We also had the latest revision of the V2R pipe. The car this time is a larger displacement TL Type-S with a 3.5L engine and manual transmission. As before, this car retained its standard primary converters but was equipped with an ATLP exhaust cat-back.

What we learned yesterday was both startling and a little depressing. What we learned was there are more variables involved in testing parts for the TL than we imagined before. Unfortunately, we got caught up chasing numbers that led us in circles.

The main goal of this test was not to see which pipes gain more power over stock since we do know that all the pipes gain power. The main idea here was to see how the pipes compare to each other. We know that dyno testing is really a game of relativity, and therefore bragging about specific numbers really is somewhat of a losing point. However, when comparing parts to each other, a dyno can be revealing as to what changes in parts make to the performance of the engine.

Here was our first dyno chart to share:

It is important not to take this first chart for face value, as I will explain after I outline the observations we made. In this chart, we are comparing the ATLP combo (yellow), the RV6 (purple), and XLR8 (red). The pipes were tested in that order as well, with each one showing more power than the last. The main thing we were surprised to see was not so much the ATLP was down on lower RPM torque compared to the RV6, but that it did not best the RV6 in the upper ranges as it had the last time. We saw considerably more top end with the ATLP in the previous test. We were not sure how to explain this. Also, we were initially impressed with the performance of the XLR8 part. While we did expect this pipe to have a good balance of high and low end, it definitely outshined the others everywhere. Also, it was more consistent. But therein lies what would ultimately be the undoing of the test…

Here is the second dyno chart:

At the end of the day, still somewhat curious as to why the ATLP performed so much less than the others, we put it on the car and did another run with it juuust to see if the lackluster performance was a fluke or not. Actually, we did five runs with it and got the same thing every time. The solid red line is the ATLP dominating the other two at the end of the day (the XLR8 line is dashed in this chart rather than solid). The ATLP pipe suddenly jumped a whopping 10+ ft-lbs right around 3600 RPM, and for there on up it literally leapfrogged the competitors.

What gives?

The problem lies within the car. The 04-08 TLs have a newer generation of computers in them which is constantly changing variables around, making dyno testing of this nature (just swapping parts around to see what they do) practically impossible to make any sense out of. In earlier runs, the computer was definitely functioning differently than at the end of the test. Add to this, our tester told us they were pretty mild with diving their car; they never really rev out past 5000 RPM. The car was used to driving slow basically and when it was asked to make power it didn’t know how until we flogged on it for 4 hours. This explains why as the day went on we made more and more power. Unfortunately, limited by time (and money) we had to cut it off before doing another round of tests on each pipe.

Even with that point aside, with the ignition timing constantly moving around, back-to-back comparisons are literally impossible to rely on. The result of this, in my mind, is that ANY dyno charts shown for an 04-08 TL (and I am sure many other car this applies to as well) are definitely to be called into question. And this has nothing to do with the integrity of the test itself or the people involved because the one main variable at work is something that to this point is relatively uncontrollable: the car’s computer.

However, all is not lost. We will be back at the dyno with a programmable computer to lock in a base map tune, and that will allow us to see which pipe makes what power and how. This likely won’t happen until the first quarter of next year. Until then, I am afraid it is still a bit of a guess as to what part really is the best one for making low or high range power. Even the information we got in the past has to be questioned to a degree.

V2R update: While we do have to bring into serious question all of the numbers this day, we do have reason to believe that the V2R prototype we tested certainly is capable of making more power than the others in this test. We feel confident that with a locked base map we will be making more power than the others here while having a lighter, stronger part with top-notch fabrication.

Intake & Exhaust

Intake Shootout! 2004-08 Acura TSX Intake Systems Compared

Heeltoe’s Intake Shootout, 04-08 TSX

An air intake is probably the most commonly purchased power bolt-on item in the automotive aftermarket. Everyone is on board with the idea that a higher flowing intake system is a great way to change the power of the car (typically for the better). However, it is interesting how different companies formulate their designs. Fluid dynamics is a tricky science, and sometimes the more obvious solutions are not the best. Likewise, the more complicated answers are rarely the best for any given question. The only way to really see how designs compare was to do a dyno comparison.

The main categorical difference between intakes is between “short ram” and “cold air” intakes. The typical chrome tube with an open-air element filter on the end is a prevailing design cue, however, where that filter is located can change the power that is created. Systems that locate the filter in the engine bay are known as short rams. This is in contrast to longer-tube systems which place the filter outside the engine bay (usually behind the bumper) to draw in cooler ambient air. The physics at play is that cooler air is denser with oxygen. Since engines produce power by igniting mixtures of oxygen and hydrocarbons, the more oxygen in the intake charge, the higher the power produced. Playing in the cold-air field are ice-boxes, which are generally systems where the filter is a panel or cone housed inside an enclosed chamber with a tube running to an area with cold-air supply.

To get some contestants, we actually checked our own site to see what offerings there were for the TSX, as this is the car we’d be testing. The usual players were no brainers. The best-selling CT Engineering Icebox, the presumptive power producer Injen SP, and what intake test would be complete without K&N and their Typhoon? A few others added some spice; A’PEXi’s Power Intake, Trust’s Airinx, and Weapon-R’s Secret Weapon all provided some contrast for the test. Our initial plan for this test was to include a larger array of intakes including a Mugen Intake and J’s Racing Tsuchinoko (both ice-box type designs), however, cost and availability limited the test to only ones that people regularly purchase. People buying J’s and Mugen many times value the brand over the benefit, although we do expect both these systems are admirable performers. An HPS entry was requested as an “eBay” entry, however, again, supply issues got in the way. AEM Induction declined to participate (we suspect parent company K&N wanted to shine brighter).

The testing was done at Church Automotive Testing, one of the best in the business. Dynapack chassis dynamometers provide a very low degree of drivetrain loss making them sensitive to small changes. The installation of the intakes in this test was of the “quick-n-dirty” methodology without taking the car off the dyno. For the most part, we did not affix the clamps or tubes that would serve as permanent installation requirements. For the 3-4 pulls on the dyno we were doing, and given that were being charged by the hour, it seems perfectly fine to do things this way. If there is any dispute in the power numbers we are providing, I would kindly suggest such scrutineers validate themselves by testing on their own. The entire test took about 2 hours, and the ambient temp was about 84 degrees F. No tuning of the computer was done to complement these intakes as that would have been too costly in time and resources. The test TSX is not equipped with a reflash of any kind.

The point of this test is not to see how much power each part makes, because every car is going to have a different result based on the other mods it has (Incidentally, our HTSpec TSX was equipped with a Fujitsubo exhaust and UR Pulleys at the time of the test, otherwise it was stock). Instead, we wanted to get them all cycled through on one car with static conditions to see how they performed relative to one another. We are not able to publish every chart, and honestly, since we didn’t have a stock intake to compare everything to it seemed like it wouldn’t be necessary.

We also took sound clips from each intake from inside and outside the car. This was in an effort to really show readers how the intake sound changes the attitude of the car, and to see which intakes sounded “better.” Much to our chagrin, the videos really did not reveal much of a sound difference at all, and even in person the only intake which seemed significantly different from the others was the only one without an open-air element; the CT Engineering Icebox. You are going to get a lot more noise with wide-open throttles with an open intake. The sound of the intakes in many cases over-powered the exhaust sound while doing this test. Most people don’t make a fuss and even like the sound, as with normal driving, you don’t hear much of anything in terms of noise. That being said, we’ve been in automatic cars with intakes and nothing else, and they can get pretty boomy.

To help make this one of the most informative tests we could, we are also critiquing the packaging quality and highlighting the CARB status of each intake. Being smog-legal is a make-or-break factor in many people’s purchase choice. Without further delay, here is what we found out!

Trust/Greddy Airinx: #6

First up we have the Trust Airinx. Trust, the parent company of Greddy Performance, is a trusted name in the Japanese aftermarket. They have a long history of producing some really high performance items for cars, especially with turbo applications.

This intake is not normally available in the USA and we had special ordered it from Greddy a while ago. It took about 60 days to come in. The box is small and light but was packed well to avoid product damage. This intake is not CARB exempt.

We were surprised to see how simple this part was, the kit containing only three pieces. A nicely fabricated intake tube, an adapter to mount the filter, and a high-quality filter assembly with replacement element. We had heard in the past that foam filters perform better than cotton ones, so we thought while this kit seemed like it had little engineering work done to produce it, it might show well by having really low restriction.

Upon closer inspection, we were happy to see that the filter adapter had indeed a greater amount of detail work than we expected. The ring locks into the toothed flange area on the chrome filter assembly for a simple, hardware-free fit. Also, it has a curved surface lending us to believe it would promote better airflow around the inner boundary of the tube.

Here you can see how the filter installs. Much better than the typical band-clamp that you see on every other part out there.

Once installed there is a completely smooth transition from the filter to the tube. While we are not sure how much this detail work actually benefits performance we can say that there was considerable effort to reduce as much restriction as possible.

Installation was stupid-simple. One bolt which is re-used on the car already, tuck the inlet pipe into the OEM intake arm, and you are done. We think a pre-schooler could figure this out. Given this was a Japan-special order item and the instructions were not much help, this is a good thing. It also looked great under the hood, giving a splash of glitz and color to an otherwise plain engine bay. This is the only yellow filter we know of.

Power notes:
The short tube, foam filter combination did no favors for the HTSpec TSX. It registered a paltry 212 horsepower on the dyno. This was the lowest power-producing part we tested. We suspect this arrangement works really well on a forced induction car where more suction is created by the engine and the length of the tube is irrelevant. This design does not translate over to NA 4-bangers if this is the case!

PROS: Low cost for high quality, Easy Install, Exclusivity of rare JDM item, Underhood eye-candy.
CONS: Didn’t produce on the dyno, Need there be anything else to avoid recommending it?
VERDICT: Stick to Supras Greddy, Trust us.

Weapon-R Secret Weapon: #5

Next up is the Weapon-R Secret Weapon Intake. Weapon-R produces A LOT of parts. Historically, they have been somewhat of a cheapish brand, producing whatever seemed trendy at the time for a low cost. Even now their site has nearly as many scantily clad models on display as it does car parts (Hey, don’t leave now! Check it out after reading our article!). That being said, it was made pretty clear to us that the Secret Weapon intake is not to be taken lightly. It does have some interesting features that make it different from the rest of the contenders here.

The packaging is quite intricate. The filter is sectioned off, and the piping is in bubble wrap. Packing seems quite safe 🙂 Nothing worse than getting a kit like this only to find parts are missing or damaged.

Pipe material is a raw, polished aluminum that looks pretty nice. The diameter is about 3″ (metric size). Raw aluminum can have somewhat of a dull look to it, however, the Weapon-R looks quite good. The logo and patent information are actually imprinted on the part itself. This is actually a pretty special cue…one of our with parts today is that they all seem to be the same thing repacked and relabeled. Weapon-R values their identity and highlight their legitimacy with details like this. Even their band clamps have their logo.

Weapon-R has created something different than the mainstream, and something important enough to patent!

Here we see what is different…this inserts in the piping. This must be the “secret.” Very interesting! Perhaps this design is to encourage a more laminar flow through the turn in the pipe. Not sure…a dyno should tell us if the sound or power is different on this kit than the rest.

The filter itself uses a foam element. As mentioned with the Turst intake, we heard in the past that foam actually promotes the best airflow as a filter substrate. If that is true the choice of foam was good in this case. The filter is a highly engineered design. It looks in itself to be a well-made part. This filter has an exposed surface area around the outside, as well as a secondary open surface on the top with an “inner filter.” There is also a flange on the top and I was wondering what that was for…

And here we go! The intake actually comes with a snorkel that will draw cold air from behind the bumper. We guess this is the other part of the secret. Under the hood, you see a Short Ram Intake, but the snorkel actually makes this somewhat of a Cold Air in disguise.

We are wondering though much cold air is drawn in with this configuration since the outer surface of the filter is still open to draw in under-hood air. We will see if there is a power difference in both configurations.

The kit comes with decent hardware and looks to be quite complete. All the intakes in this test have permanent filters, and you can get cleaning kits for them online. However, the Weapon-R Secret Weapon was the only intake in the test to come with a filter cleaning spray

The instructions are in English and look fairly complete. They are a bit general but intakes are fairly easy to install. The hardest part, in this case, is getting the stock stuff out, and Weapon-R leaves you a little on your own there.

Installation of the Weapon-R Secret Weapon intake was reasonable. The pipe could have fit a little better, and I prefer the auxiliary inputs for the breather and IAT sensor of some of the other parts better. However, this part certainly did fit fine.

We decided to run the test with and without the snorkel tube on it. It was easy to fit the tube to the end of the filter and route it to the bumper. The HTSpec TSX is running a EuroR front lip but does not have fog lights installed. This provides ample air to the area where the cold-air intakes draw from. The tube on the Weapon-R was shoved right up to the fog hole, which we imagine would give more of a ram-air effect.

Here you can see the air inlet created by the fog lamp hole, and the Weapon-R intake snorkel right inside. This seemed like an ideal mounting point.

The Weapon-R performed easily as well as the other short rams in the test given consistent temperatures. When tested without the snorkel, we did see a lot of loss to heat soak. Run after run the power was dropping (more than with the other short rams). Once the snorkel was put on we did not see any power increase however the power stabilized quite a bit. We were able to do multiple runs without losing power to heat.

We think this is because of the extra material built into the tube near the throttle body. As heat builds under the hood the tube gets hotter, which in turn heats the internal structure Weapon-R devised. This probably is serving a good purpose for airflow however it could be acting as a heater for the intake charge as well. With the snorkel on, the tube is supplied with a cooler intake charge which, instead of gaining power actually counter-acts this heating. We are speculating, but it seems like they would be better off without the extra bits inside the tube, or possibly make them in plastic instead of metal.

PROS: Different from the rest, Unassuming appearance, Quality tube and filter, The most “complete” kit with cleaning spray.
CONS: No better than the average short ram, The brand-conscious might look past it.
VERDICT: The secret’s relevance was lost in translation.

A’PEXi Power Intake: #4

A’PEXi’s Power Intake we had high hopes for. Yes, we know it is a shorty. Yes, we know it isn’t CARB exempt. But it does represent a really great value as the cheapest in our test. Also, we had heard of testing done year ago that placed A’PEXi’s filters very high on the performance scale, not just for airflow but for actually cleaning the air as well. In looking at it, this part represented a good comparison to the Trust/Greddy part as it is close in design but with a different element.

A’PEXi packed the parts well, providing instructions that are all in Japanese (not much help but pictures are provided to aid). This was a pretty simple kit though to that wasn’t a bother.

And here it is. The Power Intake consists of A’PEXi’s proprietary filter, a 3″ stainless steel tube, and a couple mounting brackets. Stainless is a good choice compared to aluminum as it doesn’t transfer heat as quickly. If fed cool air, this pipe could feel warm on the outside but actually be pretty cool on the inside still.

There is also a supplied foam strip that is supposed to provide a seal at the body gap between the fender and the hood. The idea here is to prevent water intrusion at that gap in the rain. Many people think short rams are immune to water issues, but this is not the case. There is no risk of hydro-lock, but a saturated filter will definitely reduce power and can even stall the engine or prevent starting.

Here is A’PEXi’s filter. The part is all hard plastic, with the open element around the outside. The cone shape protrudes inside the filter body.

It is difficult to see but the cone inside protrudes pretty far in. This is supposed to aide airflow somehow. A similar idea to the air-horn many companies use, however in reverse we guess.

Also, note how the filter mounts to the tube. No silicone and band clamps here. All bolts and secure hardware. We do find it interesting how both participants from Japan have more dedicated mounting solutions for their filters. Worm-drive clamps, while effective, are not very elegant.

Here is the A’PEXi Power Intake installed. This was ridiculously simple, almost as easy as the Greddy. We also think it looks great. The stainless piping has a high-class look to it, and the filter looks like it means business. Normal cotton air filters are pretty generic looking and this one is definitely not categorized this way.

Power Notes:
As a short ram, we were not expecting much and since didn’t get much but weren’t let down much. Right around 215 hp and 178 ft-lbs, this intake was nearly identical to the Weapon-R. Unfortunately, it seems like A’PEXi is more experienced with turbo cars, similar to Greddy, as it didn’t produce numbers that say “you have to buy me!” Hey, Japanese guys, NA cars like cold air! That being said, this intake did not seem prone to heat soak in the way we expected.

PROS: JDM with a low cost, High-end materials, Great filter.
CONS: Not a cold air kit so the power is down, Not CARB exempt.
VERDICT: We’d never tell you not to get this one, but beyond the brand and cost we would have a hard time promoting it.

A’PEXi Power Intake Versus Weapon-R Secret Weapon

Here we see a dyno comparison of the Weapon-R Secret Weapon (red) versus the A’PEXi Power Intake (white). Even though the A’PEXi has a little mid-range torque advantage the overall graphs indicate these parts are pretty interchangeable in terms of the output. Both bested the Greddy no problem. The slight power difference is what gives the A’PEXi the nod over the Weapon-R. We’d like to see what the A’PEXi does with a longer tube though.

Injen SP Intake: #3

When we announced this test on, the vast majority of people were focused on the Injen intake as the power winner. We have to admit, that was the outcome we expected as well. We were really surprised to see that was not the case, and this resulted in their 3rd place ranking. Really, it could be considered more a tie for 2nd place, but there are factors outside power putting the Injen where it is.

Also note, that despite the fact it isn’t indicated on their website or their downloadable instructions, this intake is CARB exempt and therefore street legal.

The packing here is seriously thorough. Similar to the K&N which shares a short-ram/cold-air configuration option, there are a lot of parts in the Injen kit. They have packed them masterfully.

Here is how the Injen looks in short-ram mode.

The elbow going to the throttle body is a really nice piece making it a little unique in design. Many users have this intake already and like it. This inlet tube is a pretty huge 3.5″, the largest in this test. Interestingly enough it necks down to 2.75″ at the throttle body side of the rubber elbow.

While we are looking at the Injen here as a short ram we wanted to address the possible question asking why would this be a desirable feature? It is mostly because of fear.

Cold-air systems place the air filter behind the bumper much lower to the ground. There have been horror stories for years about cold-air intakes sucking up water when it rains. We would like to formally clarify and refute much of this claim.

Yes, while the placement of the filter does make it more susceptible to water this is only the case in situations of flooding. WHEN INSTALLED CORRECTLY, the air filter will be completely protected from splashing water by the bumper, fender liner, and splash shield. Simply driving in the rain–even torrential rain–is not enough to cause the engine to ingest water. One would need to drive through a flooded area to hydro-lock the engine. If someone doesn’t have enough sense to drive around floods (not a puddle, or a deep puddle, actual flood conditions 6-8 inches deep) or fails to properly install their splash shields, the cold air intake should not be falsely demonized.

Here is the intake in cold-air form. The extension tube is 3″ in diameter and connects directly to the 3.5″ intake tube with supplied hardware. Piping is polished aluminum, but it should be noted that this kit comes in a black powder-coat finish as well for a more subtle look under the hood.

Injen, like all the other open-air filter elements here, is proprietary to them. It is nice to see this detail.

Here is the short ram installed on the car. The fitment is pretty good, although Injen, unlike any other competitor, decided to design their bracketry so that the mounting location is on the battery tie-down post. This seems convenient but can really cause an issue for people who change batteries, especially to smaller ones, with custom brackets. Also, since this is not a really hard mounting location, fitment can be difficult and gets even worse if someone installs a throttle body spacer in addition to the intake, or installs a different manifold. No clear alternative mounting can be arranged if needed. This might be a niggling concern but it is something that has always irked us about this intake.

We have to make an apology here as we neglected to take a picture of the cold-air installed. If you can imagine, simply extend the polished pipe until it is out of sight and you have it.

Power Notes:
In short ram configuration, this intake performed like a short ram. The chart is relatively similar to the previous short rams, albeit with a smidgen less torque. We will call it even.

When compared to the other big players here, the CT and K&N options, we were surprised to see this intake perform no better at all than the Icebox, and literally poorly when compared to the K&N. The torque figure is 181, more than the short rams. But the power at 215 hp was not impressive. It scarcely made more top-end power than the short-ram version of itself.

We were speculating on how this could be. My personal thought is that the pipe is just too big. The engine in our HTSpec TSX is not modified in a way that such a large diameter is warranted. Bigger isn’t better in many cases actually. We were told by Injen to monitor AFR readings during our test and found that they consistently hovered right under 13:1 for all parts tested, meaning the engine was pretty consistent in reading intake temperatures and pressures. Perhaps a retest on a later date with more mods on the engine will reveal some more expected findings, but right now we are forced to deflate Injen’s ego.

PROS: Looks great, Has a sound that street turners like, Pretty popular so there are plenty around for easy purchasing, Two color options.
CONS: Little bite to match the big bark, Louder than more conservative drivers might want.
VERDICT: This option will always sell well and is a staple for Acura tuners, but isn’t the winner today.

Injen Short Ram vs Cold Air configuration

CT Engineering Icebox: #2

Showing up without a real fancy box was the CT Engineering intake.

Packing is nice and neat. There isn’t much risk of damage to these parts since they are pretty durable.

This part is made of molded plastic and therefore has the most stock appearance. Also, since it uses the stock intake tube, it is much less prone to heat soak than the metal pipes. The box utilizes an upgraded panel filter which has a foam substrate with an oil catch particles. The upper lid bolts to the factory lower lid, and the resonator chambers behind the bumper are replaced with an air-horn that promotes faster ingestion of air.

Overall, a really simple kit and that comes through in the price, which is neck and neck with A’PEXi for being the cheapest one here. However, there is an important product update we are announcing here: CT is offering the lid material in Carbon Fiber as in addition to the plastic previously used. We had the great fortune of being able to test the very first prototype CF box for this test. While the plastic lid functions well, it is a plain black finish; the new carbon part looks amazing. More pics and pricing details will be announced later.

The Icebox is more than just a plastic lid, as the inlet tube has a nice air horn design. This will dramatically smooth intake airflow as opposed to a straight-cut pipe. The stock airbox has a similar design. However, the stock airbox also has stiffening ribs all on the inside which could interrupt airflow. The inside of the icebox is completely smooth.

Previously, people had issues with installing the Icebox lid onto the factory lower box. This is largely due to the difficulty in producing molded plastic parts. Temperature and material volume must be carefully controlled, which is really hard to do if you are not spending five or six digits on equipment. We assume CT is not. Carbon is a lot easier to consistently produce.

The install of this part was a little better than the previous design. You are supposed to reuse the stock airbox bolts with this lid, but we are finding that longer bolts would make things nicer. If longer bolts come with your Icebox, you can thank us for that.

What we like most about this intake is the sound. With all the other intakes here, under wide-open-throttle, they get pretty loud. In the case of the Injen and the K&N it almost gets too loud to talk inside the car. The CT Icebox keeps the noise level to a reasonable volume by placing the filter inside a box (just like stock…hmmm). It gives the engine an aggressive growl without making it a teenager’s car.

Power Notes:
Everyone we spoke to assumed the CT would be producing less power than the forum favorite Injen, even CT themselves! A little searching would provide lots of annoying posts about “searching more” etc when someone would ask what intake makes the most power, or whatever. Here, we have proven that there is no such thing as conventional wisdom. The parts need to be tested…period. Even if the Injen in our test was not well represented, we proved that the Icebox isn’t a dog compared to it.

The CT gives up little or no power to the Injen at all. While the Injen didn’t show us impressive numbers itself, we now know that the CT is not to be taken as a low performing part as it did fare much better than then short rams. It also has a really nice torque bump between about 2300-2800 RPM, something that was consistent amongst all runs and didn’t show up on any other charts. We believe the large volume of the Icebox gets the credit here. An initial charge of air is ready to get ingested right as the throttle is opening. However, we are looking at the horsepower figure and thinking that there is something lost in air velocity as the revs climb. Yet, at the very peak, it matches our power winner making a solid 7 hp more than the lowest performer here. Results were pretty consistent as well since the composite materials don’t have nearly the heat-soak factor (again like stock, interesting).
The most impressive thing about the CT Icebox? It is made by a company that isn’t an intake company! CT considers itself a supercharger company. When comparing this product to other solutions, we feel they should be proud to be listed high up among the other intake-only companies in this test.

PROS: Low cost, Very simple kit, Makes power in-line with the best of them, Less prone to heat soak because it isn’t metal, Sound isn’t intrusive…actually sounds good!
CONS: The plastic is ugly and pricing isn’t yet available for the CF, Could fit better (even the CF one).
VERDICT: Bottom line, the HTSpec TSX arrived at the dyno with the CT Engineering Icebox on it, and left with it on as well.

K&N Typhoon Intake: #1

Here is the K&N Typhoon, our winner. Let’s look at what made this intake the top pick.

The packing is really good, similar to Injen. This kit also comes with an Air Filter Wrap which is supposed to help prevent water from saturating the filter, but as we mentioned we don’t think this is a big concern.

Here is the kit. The piping is the smallest here, suspiciously close to the diameter of the throttle body at approx 2.75″. This pipe was the smallest one in the test and was consistent in diameter throughout. The material is aluminum however it is not polished. It has a painted chrome finish which seems odd but possibly more durable. One of the pipes did have a flat at the opening, which wasn’t a big deal but was a little surprising to see. It could have come from a chop or band saw that had too much pressure. It wasn’t going to be visible or affect performance…no biggie.

K&N’s name is legendary in the performance filter market. Everyone else after them really seems just like that…followers.

Here is the short ram installed. Of the short rams, this one does look aggressive. The filter is really large and the placement is nice. It looks like even though is a short ram they made it as long as possible. The mounting is very simple, one bolt in a factory location.

Here is the cold-air version installed. It also fits well, and if we preferred the chrome-tube look would take this one over the others.

Power Notes:
What can we say, this one has a huge bump in torque over the others all the way from 3100 rpm to over 5000 rpm maxing out at 186 ft-lbs, 5 more than the CT and Injen. After the VTEC point at 6200 or so, the torque makes another appearance, again almost 5 ft-lbs more than either the CT or Injen can muster. This translates to a nearly consistent 3-5 hp improvement over the Injen on the power side. The CT is a closer rival but still doesn’t offer the power of the K&N overall.

It is possible that with a highly upgraded engine this intake could be more restrictive, but the level of upgrades most TSX users get into will not likely approach this limit until we are just this side of boosting the engine.

PROS: The most power and torque we had seen, Great fit, Solid name.
CONS: Not really polished, Will be noisy, Higher end of cost spectrum (excluding JDM offerings).
VERDICT: It wins the power race, if you are into the chrome pipe thing look no further.

CT-Engineering Icebox versus Injen Cold Air versus K&N Typhoon

Graph showing our top three finishers. K&N is the red dashed line, CT is the green, and the Injen is the solid red.

The K&N clearly has an advantage here. It is hard to ignore the fact that CT makes more torque and power where the others cannot, below 3000 rpm. Automatic Trans drivers will appreciate this.

One glaring issue is what happens at about 6200 rpm, where the TSX with a stock tune has the VTEC point way too high. We can’t see the logic in this, but we have definite plans to fix it!  A Hondata reflash is planned for our next trip to the dyno. At that time we would like to retest the top three finishers here in a more strict power test after installing a heatshield gasket. We’d also like to confirm is the P2R throttle body spacer is as good as we hear it is. Until next time!

Intake & Exhaust Universal Fit Blogging

Heeltoe Automotive Takes Over ATLP Production & Distribution: Celebrate With Us!

There are times when things come full circle and seem oddly appropriate. There are times when there is a certain satisfying irony the accompanies a change in my life or my business. There are times when I remind myself that luck is the product of opportunity and preparation.

This is one of those times.

In an effort to grow business revenues, strengthen our presence in the Acura enthusiast market, and provide a greater sharing of our abilities to a wider base of customers, ATLP is now a wholly-owned subsidiary of di Sabella Industries, Inc., the parent company of Heeltoe Automotive through a buy-out transaction.

Celebrate with us now by pre-ordering the ATLP product you’ve been waiting for using coupon code “atlppromo” when checking out online. At this moment we do not have any active group buys going on. When we do, we don’t believe the pricing will be better than this coupon is offering. Play with the coupon on now!

Mike Yu developed ATLP out of nothing. “I’d like to make exhaust systems,” I remember him telling me one day as we were tinkering on his TL. Having been in business for a number of years prior to that moment and finding the trials and tribulations to be those which, should they feel up to the task, every American should experience, I encouraged him as much as I could. Ultimately it was up to him to pull the trigger; a rare American indeed possesses such courage. Not too long after that time we got the Quad exhaust, the first effort put forth by (later to be known as ATLP Lab). Then more innovative exhaust products would come along to support sales even more.

ATLP’s business became stronger because their exhaust parts have a special set of attributes that consumers love. A high-class look, amazing sound, awesome performance, and attention to detail. Satin-finished stainless pipes, laser-etched tips, and innovative designs are even more values customers clamored to own. ATLP parts became a hot seller for Heeltoe Automotive, as we were honored to be brought into the dealer program they set up. We’ve run about 4 group buys for various products, all of which were very successful, culminating in about 5% of Heeltoe’s total sales volume for 2010. ATLP was successful enough for Heeltoe, it made me wish for an exhaust line to call my own. Having been an employee at Magnaflow for a few years I know the aftermarket exhaust industry as one second only to the aftermarket wheel industry.

I didn’t need to wait too long for my exhaust-brand wish to come true. Mike, having set his focus on a new course of business, decided it was time to move on from developing ATLP. I am thankful he decided to look no further for a successor to the ATLP helm than Heeltoe Automotive. Citing our ability to faithfully continue the ATLP brand in the same spirit as he did, expecting we could grow the brand and honor its principles, Heeltoe was clearly the fated destination for this illustrious product line to live on.

In much the same way Heeltoe procured Fastline Performance and Maven Motorsports in an effort to continue serving customers with their truly excellent products, we plan to continue to strengthen the ATLP brand into a product line that we can be even more proud of. Here is a breakdown of what you can expect over the next 12 months:

  • New production runs of 3rd Generation TL exhausts, both the Base and Quad systems
  • Special promotions
  • New products for more applications (first up is a Quad exhaust for 4th Gen TL SH-AWD models)
  • Fast customer service, and hopefully faster shipping times, the way you know Heeltoe can deliver it

Keep in mind, the business change is still in transition. While all the details of the change are done, the moving of the website, email, etc are all still being coordinated. Please be patient with us in the meantime.


Thank you so much for reading, and hold expectations of your new year as high as we all do here at Heeltoe Automotive!

Heeltoe Explains Intake & Exhaust

An Outline Of The Exhaust Layout On J-Series Honda/Acura V6 Engines

Updated Nov 9th, 2016

Later model Accords from 2013 and newer have a little different layout where the catalytic converter that used to be after the j-pipe is now incorporated with it. So replacing the J-pipe is now something that will also replace the cat.

The J-series Honda V6 found in all V6 Hondas and Acuras since 1998 (such as the Accord, the TL, the MDX, Odyssey, Ridgeline, and even the limited production TSX V6) has a special cylinder head that has a manifold integrated into it. As such, there is only a single port coming off the head that leads to the exhaust system.

Early J-Series

The first generation of the J-series found in 01-03 CLs, 98-02 Accords, and 99-03 TLs featured a traditional manifold layout with a front and rear bank of primary tubes that heads down to a collector.

1g J-series header from CT Engineering

Later J-Series, “Pre-cats”

Later 04+ J-series engines have quite a different design.

Diagram of the J-series cylinder head showing a single port.

The single-port then dumps directly into the “pre-cats” as people refer to them. As a matter of fact, these are the primary converters in the car, containing 2 O2 sensors each. These cats are restrictive and are frequently removed (albeit illegally) in favor of open units, which we are told make a significant power increase. RV6 Performance makes Pre-Cat Deletes. Often these are referred to as PCD’s throughout the web. Deleting these converters will cause and engine light to come on, but the RV6 pipes do come with provisions for fooling the sensors so the light does not come on.

RV6 Pre-cat deletes. RV6 also produces versions of these pipes with metal-core converters, called High Flow Pre Cats, or HFPCs.

J-pipe as the new “header”

Immediately after the pre-cats, there is a “j-pipe” as has been dubbed by the industry. This pipe takes the flow from the front and rear bank cats and brings it together into a single exhaust system. There are significant gains to be made from replacing the factory j-pipe to an aftermarket version. Larger diameter piping and a smoother collector improve the volume capacity and flow of the system. RV6, ATLP, and XLR8 all make j-pipes for the TL/Accord. We prefer the ATLP version as it has been redesigned to allow more ground clearance due to customer demands and produces maximum power in the upper RPM ranges. The others may have been updated recently, but ATLP remains our preferred brand because it’s the price point is competative, ability to keep the stock cat and provide a lot of ground clearance.

ATLP J-Pipe, smooth transition, large piping, ground clearance, can use stock 3rd cat.

The 3rd Cat

After the J-Pipe there is the 3rd cat. This cat, which lacks any O2 sensors, exists to provide additional of the exhaust not taken care of by the pre/primary converters. This pipe can also be replaced by a test pipe or a high-flowing converter to produce more power. ATLP, RV6, and XLR8 all make both options to replace this converter, although it should be noted that replacing this converter is completely illegal as well, however, deleting it will not cause any engine lights to come on.

ATLP Race pipe, a 3rd car delete.