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673 Posts
Discussion Starter · #1 · (Edited)
Note: Posting on Ken's behalf.

In May 2003, I developed an article for entitled Clash of the Titans. Four exhausts were invited to a proposed shootout held at SP Engineering in the City of Industry, CA. Invited participants included the GReddy Power Extreme, the VeilSide Titanium, the Blitz Nur Spec R and the HKS Racing Titanium. Of the four exhausts, three showed up for the shootout (the Blitz Nur Spec R was a no-show) which was, ultimately, won quite handily by the HKS Racing Titanium.

Fast forward to May 2005 and circumstances have changed quite a bit. For starters, this time I’ve written the sequel to Clash of the Titans I for SupraForums, by all accounts considered the largest, most successful and influential Supra-based website on the Internet. Secondly, the HKS Racing Titanium has some very serious 4-inch exhaust competition. No longer can it expect to win exhaust shootouts just by showing up. In Clash of the Titans I, it was the biggest and straightest exhaust in the competition, so no surprise that it out spooled, out powered and out torqued the competition. The big question for Clash of the Titans II is would the HKS be able to stand up to bigger, better and much newer competition? Read on and find out.

As the MKIV Supra aftermarket has evolved and matured in the U.S., a few innovative and courageous manufacturers have stepped up to go head to head with Japanese aftermarket powerhouses, such as HKS, GReddy, VeilSide, Blitz and others. One area where this trend is apparent is in the research and development of big-bore 4-inch exhausts for the MKIV. With all the new, and some old, competition, it only made sense to gather together all of the mass produced 4-inch exhausts, identify a car capable of exploiting these exhausts in its STREET tune, bolt ‘em up, lash the car down to SP Engineering’s Dynojet chassis dynamometer and clear up all the “mine is bigger, and badder, than yours” smack talking so prevalent in the Supra community. First up, the new kids on the block:

One of these “new kids” is Wide Open Throttle Motorsports (WOTM), the progeny of founder and owner Ryan Woon, a guy who has also developed somewhat of a reputation as a pretty good engine builder and six-speed drag racer. Wanna’ see how well WOTM parts work on a big power MKIV Supra? Pay attention the next time you see Ryan’s car at the races or in a show and shine. The WOTM exhaust is a two-piece all stainless steel sewer pipe that weighs in at an even 22 lbs. Add the assorted hardware and bracketry and the total weight goes up a bit to 24.3 lbs. It also has an exhaust tip ID of 98 mm and a piping OD of an even 100 mm.

Remember the old biblical story of David and Goliath? Well, we have our own modern day Goliath in the form of the HorsepowerFreaks (HPF) Goliath 4-inch exhaust for the MKIV Supra. All it took was one email from me to Chris Bergemann, founder and owner of HPF, and he immediately agreed to participate in the shootout. “Where do I send it and when?” was all he asked. This exhaust is fully polished T-304 stainless steel and comes with a patented Aero Turbine muffler that is said by its manufacturer to actually speed up exhaust flow. Weighing in at an even 24 lbs., 24.5 lbs., with the “V” band, the Goliath came ready to do business. We measured the ID of the exhaust tip at 103 mm, and the piping OD, like the WOTM, came in at 100 mm.

The third company in our new kids threesome is BoostLogic, builder of very high quality, turbo kits, drag race auto trannys, crank dampeners and exhaust systems for the MKIV. Founded and owned by Kean Wang, a name well known to MKIV enthusiasts everywhere, the Boost Logic is also a fully polished stainless steel 4-inch exhaust that, according to its supporters, is ready to seek out and destroy the competition. Kean immediately agreed to ship an exhaust to SP Engineering and let me know in our back and forth emails how enthusiastic he was about the proposed shootout. The BL had the largest exhaust tip ID of 123 mm and a piping OD of 100 mm. Although appearing to some eyes to be physically larger than the GReddy and WOTM in particular, the BoostLogic 4-inch was the lightweight of the group, weighing in at a feathery 19 lbs., and 21.5 lbs., with hardware.

Although the product of GReddy, an old school Japanese aftermarket manufacturer, the Evo II 4-inch is not all that well known in the Supra community and was never really marketed in the U.S. Well, the results of this shootout may change all that. Made of mild steel with a polished stainless steel canister, this particular exhaust is owned by Ju-Hon Chan, the owner of the car used for testing the competing exhausts. Acquiring this exhaust on a special order basis, Chan is one of the more spirited and enthusiastic supporters of GReddy’s entry into this comparo. With matching 95 mm exhaust tip and piping internal and external diameters, the GReddy’s apparent advantages are only partially offset by its mild steel construction and our forgetfulness in weighing it on the day of the competition. This oversight will be corrected within a few days at most.

Last, but certainly not least, is the HKS Racing Titanium, an exhaust considered by many to be the undisputed champion of big-bore exhausts. Here’s the deal, though. It doesn’t matter what you and I THINK; all that really matters is objective performance (and price, looks and perceived value). Sure, it’s won virtually every competition in which it has competed, but none of those competitions, to our knowledge, matched the HKS with like-sized opponents. No light-heavyweight competition here; the HKS was, for the first time, going up against other industry heavyweights. This exhaust came off my personal car and weighed in at an even 26 lbs with everything included. As most of you know, only the slip-fit muffler assembly is made of titanium; the big-bore piping is made of polished stainless steel. Measuring the exhaust tip revealed an ID of 111 mm and, like all the others except the GReddy, the piping OD came in at 100 mm.

Black, sleek and stock bodied except for the carbon fiber TRD hood, this car, with polished OEM wheels, epitomizes all that we’ve come to know and love about the MKIV Supra. Owner, Ju-Hon Chan, graciously volunteered the use of this car for Clash of the Titans II long before the arrangements were made to acquire the various exhausts. Because of significant demands on my time, causing a number of unavoidable delays in the proposed competition, Ju-Hon used the intervening time to build up his car. Although the mod program has been comprehensive and balanced, our focus is, necessarily, on the motor, as these exhausts love to make big power.

Heading up his list of motor mods is a pair of HKS GT2835R turbochargers (56-trim; 0.61 A/R) with custom SP Engineering 100 mm intakes and JetHot 2000 ceramic coating on the twin HKS manifolds, turbines and downpipes. HKS rates these turbos at 420 ps each, with the only difference between these turbos and the 56-trim GT2835s being the 100 mm intakes. Also from the HKS catalog are 264-degree cams, intake and exhaust, its original five-bolt cam gears, the Type DLI ignition amplifier, EVC 4 boost controller, triple-disc clutch with slave cylinder mod, 1000 cc fuel injectors, dual in-tank fuel pumps and the HKS F-CON V-Pro EMS.

The HKS pieces are ably assisted by a built shortblock with a lightened, knife-edged, polished and balanced crankshaft, Crower billet steel connecting rods and forged JE .040 overbore pistons with a static compression ratio of 8.5:1. The shortblock is sealed with an HKS metal head gasket, and topped by a ported and polished cylinder head stuffed with Ferrea valve train components. Although not yet tapped out, the motor recently made 813 whp on 100-octane unleaded and recently completed its C16 mapping. As noted earlier, the decision was made to dyno the car utilizing its STREET tune, as it was felt everyday performance was more important to the community than dyno-optimized performance. Besides, no tuning was allowed, so we had to be sure the tune was safe and that it would allow repeatable and reliable results.

In any testing of competing products, you want to limit, to the extent possible, variables that might negatively impact the integrity of the test protocols employed, or the reliability of the results generated. For this particular event, we agreed before hand to use C16 racing fuel, boost to 1.8 kg/cm^2 (25.56 psi) and to dyno each exhaust a total of three times, with no cool down period between dyno runs. As with Clash of the Titans I, we proposed a cool down period of one hour between the last run of a particular exhaust and the first run of the succeeding exhaust, although we opted to reduce the cool down period to 45-minutes once testing began.

673 Posts
Discussion Starter · #2 · (Edited)
In Clash of the Titans I, we were using Bill Robards’ extraordinary electric blue with purple pearl 1997 wide body. Much care was taken getting Bill’s car on and off the lift for the three exhausts tested, using a good portion of the hour allotted between each exhaust. In the case of Chan’s stock-bodied, stock ride height car, we found that the SP Engineering crew was very efficient and the car was ready to dyno with the next exhaust much earlier than we had anticipated (Jason Reinholdt of SPE worked alone on Robards’ car the first time around). This efficiency, combined with temperate weather conditions, led us to reduce the cool down period between the exhausts tested to 45-minutes (It is noted that, due to a mistake by yours truly, there was only 39-minutes between the last run of the HPF Goliath and the first run of the HKS Racing Titanium. We do not believe the results were affected in any significant way (sorry)).

In an effort to answer as many questions as reasonably possible, we purchased two decibel meters that were used to take readings at idle, inside and outside the car. We also took maximum decibel readings, also inside and outside the car, during the 15 fourth-gear dyno runs we carried out on the day of the testing, April 29, 2005. One decibel meter was affixed to the driver’s seat (see photos) with the window down in an effort to duplicate the assault on the driver’s left ear many of us have become accustomed to. The second decibel meter was strapped to a tripod-type contraption two feet (up and diagonally) behind the exhaust tip for maximum effect (see photos). In addition to the actual power numbers shown in “THE RESULTS” section below, we have included decibel readings for each exhaust at idle and WOT in fourth gear.

Okay, let’s get a show of hands from all of you who skipped directly to “THE RESULTS” section, lol! We understand your eagerness to get to the bottom-line, but the results would not mean much, and would be open to question, if the steps outlined above had not been taken. So, sink your teeth into this, boys and girls, and choose your weapon accordingly.

With the GReddy Evo II 4-inch already on the car, our testing began in earnest, with the first dyno run going off at 1:41:58 p.m., followed closely by the second and third runs at 1:44:56 and 1:47:32, respectively. The three runs netted power, torque and sound level readings as follows:

Run #1: WHP: 639.5; Torque: 524.1; Idle db (interior): 83.3 db; Idle db (exterior) 98.6 db
4th-Gear WOT db (interior): 105.3 db; 4th-Gear WOT db (exterior): 121.5 db

Run #2: WHP: 644.1; Torque: 522.8
4th-Gear WOT db (interior): 105.7 db; 4th-Gear WOT db (exterior): 122.0 db

Run #3: WHP: 645.7; Torque: 526.4; 4th-Gear WOT db (interior): 105.5 db; 4th-Gear WOT db (exterior): 121.8 db

The second exhaust tested was the WOTM stainless steel 4-inch, with the first dyno run occurring at 2:31:46 p.m., and the remaining two runs taking place at 2:35:02 and 2:37:42, respectively. The three runs netted power, torque and sound level readings as follows:

Run #1: WHP: 648.9; Torque: 526.7; Idle db (interior): 78.3 db; Idle db (exterior): 99.3 db
4th-Gear WOT db (interior): 106.5 db; 4th-Gear WOT db (exterior): 121.9 db

Run #2: WHP: 645.2; Torque: 524.2
4th-Gear WOT db (interior): 105.3 db; 4th-Gear WOT db (exterior): 122.1 db

Run #3: WHP: 641.1; Torque: 524.6
4th-Gear WOT db (interior): 105.3 db; 4th-Gear WOT db (exterior): 121.9 db

Up next was the fully polished BoostLogic stainless steel 4-inch exhaust, with the first dyno run occurring at 3:22:36 p.m., followed closely by runs two and three at 3:25:14 and 3:27:52, respectively. The three runs netted power, torque and sound level readings as follows:

Run #1: WHP: 645.8; Torque: 531.8; Idle db (interior): 81.9 db; Idle db (exterior): 102.0 db
4th-Gear WOT db (interior): 107.7 db; 4th-Gear WOT db (exterior): 123.1 db

Run #2: WHP: 644.2; Torque: 528.4
4th-Gear WOT db (interior): 106.2 db; 4th-Gear WOT db (exterior): 123.1 db

Run #3: WHP: 640.3; Torque: 527.9
4th-Gear WOT db (interior): 106.6 db; 4th-Gear WOT db (exterior): 123.4 db

Batting fourth and clean-up was the very shiny HPF Goliath 4-inch. Chan’s black beast roared once again at 4:13:48 p.m., and, as the db readings show, just as loudly at 4:16:02 and 4:18:54, respectively. The three runs netted power, torque and sound level readings as follows:

Run #1: WHP: 645.3; Torque: 528.0; Idle db (interior): 80.8 db; Idle db (exterior): 99.5 db
4th-Gear WOT db (interior): 105.4 db; 4th-Gear WOT db (exterior): 121.6 db

Run #2: WHP: 636.9; Torque: 523.8
4th-Gear WOT db (interior): 105.7 db; 4th-Gear WOT db (exterior): 121.6 db

Run #3: WHP: 638.0; Torque: 524.2
4th-Gear WOT db (interior): 105.7 db; 4th-Gear WOT db (exterior): 121.8 db

At the end of a long day, the project team prepared to dyno the Supra community’s long-time 4-inch favorite, the HKS Racing Titanium. So, at 4:57:52 p.m., Jason Reinholdt lit off the dyno for the last three runs of the day. The first run was followed by the second and third runs at 5:00:30 and 5:03:20, respectively. These last three runs netted power, torque and sound level readings as follows:

Run #1: WHP: 649.3; Torque: 534.8; Idle db (interior): 77.4 db; Idle db (exterior): 98.2 db
4th-Gear WOT db (interior): 105.3 db; 4th-Gear WOT db (exterior): 121.6 db

Run #2: WHP: 643.6; Torque: 525.1
4th-Gear WOT db (interior): 105.5 db; 4th-Gear WOT db (exterior): 121.6 db

Run #3: WHP: 643.6; Torque: 528.4
4th-Gear WOT db (interior): 105.7 db; 4th Gear WOT db (exterior): 121.6 db


673 Posts
Discussion Starter · #3 · (Edited)
Interestingly, the GReddy Evo II 4-inch was the only exhaust to gain power on its second and third dyno runs, hitting its high-water mark in power and torque on its third run. The other four exhausts recorded their highest power and torque numbers on the first of their three runs.

The HKS Racing Titanium and the BoostLogic 4-inch were the only two exhausts to top 530 lb-ft, with the HKS making almost 535 lb-ft (534.8) and the BoostLogic almost 532 lb-ft (531.8). In three cases, the WOTM, HPF and HKS produced the second highest torque readings on the third and final dyno run. The GReddy produced its highest torque reading on its third run. In Clash of the Titans I, we theorized that the more heat in the HKS triple, the better it would grip; hence, in some cases, the higher torque figures. Chan’s car has the HKS triple as well, but we’re really no closer to understanding this as we were two years ago.

As noted in the decibel readings, the BoostLogic was noticeably louder than the other competing exhausts at WOT and second to the GReddy in the interior idle db test (recall that increases in decibel level readings are logarithmic, so the difference in decibel level readings may be significant to some). That said, sound quality can make a significant difference as to whether the actual “loudness” factor is objectionable. In this respect, all five exhausts are very strong performers in terms of the quality of the sound emitted. By the slightest of margins over the HKS Racing Titanium, the WOTM 4-inch was considered to have the best sound quality of those tested. Also of interest, the HKS Racing Titanium, long known as one of, if not the, loudest exhaust in existence is now quite the pussycat (relatively speaking) when it comes to some of its more boisterous bretheren.

It would be difficult to prescribe a more closely packed group of competitors, with the GReddy, BoostLogic and HPF all producing peak power between 645 and 646 whp, and the HKS and WOTM only slightly separated from the pack at 648.9 and 649.3, respectively. The numbers are so close, and within accepted margins of error, a change in the order in which the exhausts were dynoed could have the effect of changing which exhaust makes the most power and torque. Other than the GReddy, which was already on the car, and the HKS, the order of dynoing was the luck of the draw. Because I personally own the HKS, and because of its reputation, I determined it would dyno last in the competition to avoid any appearance of favoritism or impropriety. Because it dynoed last, in slightly warmer ambient conditions (see dyno sheet showing ambient air temps and the correction factor on each exhaust’s highest run), and still produced the highest power and torque readings, early reports of a new king of big-bore 4-inch exhausts appear to have been in error. With such close competition, however, if we conducted this test next week, it is likely we’d have a different winner.

As noted at the outset, all testing took place at the SP Engineering facility located in the City of Industry, CA. SP Engineering ( has developed quite a reputation in the Supra community, having built and tuned numerous award-winning and magazine-featured MKIVs over the years, including Chan’s car and that of yours truly. Alex Shen, owner of SP Engineering, agreed immediately to my proposal to conduct the exhaust shootout at his shop. Shen contributed free of charge the time of Jason Reinholdt, SPE’s chief engine builder and Hiro Kondo, the company’s chief F-CON V-Pro EMS tuner and the shop’s chassis dynamometer for the entire day, telling me over the phone that, “The Supra community has waited a long time for this, so I’m stoked we can play an important role in bringing this about. Plus, we did Clash of the Titans I. It’s only natural we be involved in Clash of the Titans II.”

Having no computer or photography skills, I knew I would need someone with talent to assist me in developing this article for the Supra community. In the two years between Clash of the Titans I and II, I’ve come to know a true gentleman by the name of Anthony Marciano, owner of one of the most dramatic Supras in the U.S. Those frequenting the Members Rides subforum on SupraForums have seen first hand his skills behind the camera lens. Although this was not a photo shoot per se, with lovely and uncluttered backgrounds, I knew that Anthony’s ability, and technical suggestions on other shootout related issues, would greatly enhance the substance of the final product. A link has been included at the end of this article to give the reader a better idea of some of the other vehicular attractions that caught Anthony’s attention on the day of the shootout.

None of this could have happened without the right car and right car owner. It would be hard to imagine a more enthusiastic and supportive car owner than Ju-Hon Chan. When I suggested we limit the tests to two dyno runs per exhaust, Chan insisted on following the three dyno runs/exhaust approach we established in Clash of the Titans I. Moreover, I had to gently persuade Ju-Hon to limit the boost level to 1.8 kg/cm^2, as he was prepared to run an even higher level of boost. Because of limits on my time, Chan took the time to ensure his mid-pipe would fit all competing exhausts and obtained the two decibel meters utilized in the testing, making for a more comprehensive assessment of the competing exhausts than we were able to accomplish in Clash of the Titans I.

Many thanks also to BoostLogic, HorsepowerFreaks and Wide Open Throttle Motorsports for stepping up to do battle with the Japanese industry titans. We all know that competition makes for better products and pricing, so the Supra community has much to be thankful for as result of the free-market entrepreneurship of these companies.

During this project’s gestation, I was communicating via email with Dusty Womack, the owner of SupraForums. We agreed the competition would likely be very close, although I don’t think either of us believed it would be this close. There are NO losers here, ladies and gents. Everyone has slightly different criteria when it comes to selecting parts for our cars, be it looks, price, decibel level, materials, quality of workmanship, maximum performance or customer service. It is heartening to know MKIV Supra owners cannot make a bad decision when selecting among the five 4-inch exhausts tested in Clash of the Titans II. Until Clash of the Titans III, keep it on the road and out of the ditches. Peace.

Clash of the Titans II Photo Gallery:

577 Posts
Perfect write up. I would expect nothing less from Ken after reading his write up's for TO4r. As always, HKS delivers once again. Not taking anything away from any other builders/shops, however, I work in an Industry where competition relies heavily on other's, and if HKS did not set the standard, other's certainly would not follow (as observed in pictures showing close replications/close copies of the TI.) As stated in the article, it certainly does not look like one can go wrong with any of the 4 inch exhaust's, however, I am glad the TI (my personal favorite and on my car) still holds true as one of the top exhausts after a couple years on the market.

Thanks for those that contributed to this test...

Now only if we could see a manifold shootout in the near future...

Super Moderator
11,139 Posts
Thanks for posting for me Anthony (AMMO). A really great job. Ya got skills, my friend.

Dave Capone: We did not plan on posting sound clips. The decibel level and sound of these exhausts vary based upon individual set-ups. For instance, attempting to compare the sound quality and loudness of the HKS ti on my car, versus when it was installed on Chan's car, made such comparisons fruitless. The HKS on Chan's car was so much quieter on his car than mine, we couldn't believe our ears.

I also experienced this when I, and two of my friends, purchased the VeilSide ti. Because of the different set-ups (and total exhaust flow), each car sounded noticeably different than the others. In general, I believe a prospective purchaser needs to hear these exhausts in person.


673 Posts
Discussion Starter · #9 · (Edited)
Ken, Once again thank you for letting me a part of this big project and hope to work with you in the future. Your writing skills are second to none my friend.

Ju-Hon, It was really great meeting you and seeing your beast perform (even on street settings). Keep in touch buddy.

On a side note I must appologize for the way some of the pics came out (even though this wasn't a photoshoot by any means). I would also like to thank SPE for opening their doors to us for this project in their beautiful and professional facility.


2,999 Posts my opinion, the HKS looks like its still holding its own in the exhaust battle. great, great, great write-up. Gotta thank eveyone involved for the taking the time to give us this valuable info! :bigthumb:
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