Cold Air Intake On VW GTI VR6 - Exhaust Systems - Eurotuner Magazine

We know you've been sitting on the edge of your seat since last month when we tested every true CAI (cold-air intake) we could get our hands on for the Mk4 VR6. Well, as promised, this month we tested every exhaust we could find, and here are the results. For the exhaust test, we used the dyno facility at the Primedia offices in Anaheim, California. This is the same shop Sport Compact Car, European Car and a number of other magazines use for their testing. The facility houses a Dynojet 248C dynamometer and a full range of Craftsman tools for our greasy little hands. We tested the car over a period of two days and some of the results were surprising, even to us.

We feel a need to mention something we call a 3% error correction at this point. What this means to you is there's a 6% margin of error on any dyno test and the actual power could be either 3% higher or lower than dyno'd. So in the real world, a system that tests at 169hp could also test at either 168 or 170hp under the exact same conditions. There are actually a few systems in the test that prove this, so we wanted to ensure you are as informed as you possi-bly can be.

There were no restrictions on what exhausts could be entered into the compar-ison. So, in all fairness, it shouldn't be taken as a straight comparison. Some manufacturers only make 2.25" systems, while others make 2.5" setups, but we ran them all. We've noted the size of the systems for you, but keep in mind the 2.5" systems produced higher numbers in most cases - possibly indicating that everybody should offer such a system for the VR6.

Generally the 2.25" systems dyno'd a few ponies less, but most were much quieter than their 2.5" counterparts. So all this should be taken into consideration when making your purchase.

The real question is: Are you willing to endure a louder car for those few extra ponies? Or would you prefer more refine-ment with slightly less power? The decision is yours.

Make sure you review the following pages and keep in mind we are positive your butt couldn't feel a 3hp increase. So will your decision be refinement or power? We know which we would choose.

We've included another of our exceed-ingly creative points scales. To keep it simple, we used a 1 to 10 scale, where the average score was 5. Anything below average received a lower score and anything higher was scored higher. Sounds simple enough, but here's our feeble attempt to confuse you: We scored the systems in four categories - power, ease of fitting, finish and price. The 10-point system was applied to each category, with a possible 40 points up for grabs for each exhaust.

Power was judged on peak numbers alone, although we advise you to pay more attention to power under the curve. Ease of fitting was judged on just that - how easily the systems went on and how much mess-ing around it took to get them to look right on the car. Finish involved how the welds looked, how pretty the unit was and so on. The final category was price since we knew this is important to all of us.

Please bear in mind this test is a guide and should be looked at subjectively. In the end, you know what will best suit you, and this article was designed to be one phase of your research. Armed with this, you have to decide which system has the right com-bination of power, price, prettiness and practicality for you. Good luck.

Autotech Sport Tuning
Stock horsepower: 162.79
Stock torque: 170.16
Autotech horsepower: 170.29
Autotech torque: 178.88
Diameter: 2.5"
Price: $699.95
Contact info: Autotech Sport Tuning, 949/240-4000, www.autotech.com

After getting our baseline numbers with the stock system, Autotech was first to be tested. The system is constructed from 16-gauge T-304 stainless steel and is CNC mandrel-bent tubing. It is beautiful in its construction, and while it isn't shiny all the way back, it has the marks of a high quality unit. All of the welds are TIG, which is stronger and better-looking than a wire-fed (MIG) unit can provide. The system also uses "shell-style" clamps as opposed to U-clamps to join the exhaust sections together. This type of clamp works really well to prevent exhaust leaks and is very similar to the OEM parts.

The system bolted up easily, and its three-piece design made installing the over-axle pipe a breeze. Autotech was the only system that had a turn-down tip, and with the sound reverberating off the pavement, it emitted an eerie grumble. The system wasn't excessively loud or raspy; it just had a solid grumble that turned into a roar at the top of the rpm range.

Power output was nothing to shake your head at either. The system made 170.29hp at peak - an 8hp gain - but under the curve there were 12-14hp gains over stock and a huge gain in torque on the bottom end.

So Autotech wasn't as shiny as some other systems, but it finished with the third-highest power number, and did so without being too loud.

Euro Sport Accessories
Stock horsepower: 162.79
Stock torque: 170.16
Euro Sport horsepower: 170.91
Euro Sport torque: 181.84
Diameter: 2.5"
Price: $619.95
Contact info: Euro Sport Accessories, 714/630-1555, www.eurosportacc.com

Euro Sport Accessories entered its 2.5" system. The company does make a 2.25" system as well, but we didn't get a chance to test it because of time constraints. The well-built system is made from 16-gauge T-304 stainless steel and is mandrel-bent. It uses "shell-style" clamps, which proved to be the easiest to install. Unlike U-clamps, the shell-style clamps lock down evenly and equalize the pressure across the joint, going a long way to prevent leaks or crushed piping. The system is a three-piece unit with a separate over-axle section, making it a snap to install. You can also adjust where the tips sit by twisting the over-axle pipe while it is still loose, ensuring it's properly aligned.

The trend with the three highest horse-power systems was the "unfinished look." We don't mean they're ratty looking, but they have a raw metal finish with no polished tubing, although the tips and mufflers are shiny.

The Euro Sport system performed really well on the dyno, making gobs of power both under the curve and at peak. Again, the 2.5" tubing lent itself to a vicious burble at idle that turned into a fierce scream under throttle. The downside of the system is that Euro Sport doesn't make one for the non-cutout rear-valance cars. This means you need to replace the lower valance with the newer version if you want to fit this system to a '01-or-older Mk4 Golf.

Evolution Motorsports
Stock horsepower: 162.79
Stock torque: 170.16
EvoMS horsepower: 168.32
EvoMS torque: 178.84
Diameter: 2.5"
Price: $695.00
Contact info: Evolution Motorsports, 480/317-9911, www.evoms.com

The EvoMS system combined the best of both worlds; it was shiny and it made power. It's constructed from high-quality, mandrel-bent, T-304 stainless steel tubing for unrestricted flow. It also has a highly polished finish and aesthetically pleasing welds. This system was one of the nicest looking if you're into the whole shiny thing.

Fitting was fairly painless, and the biggest challenge was deciding which soda to drink after we were done. The system tucked up neatly and had a really nice sleeper-style tip that looks damn-near stock at first glance. EvoMS also utilizes the shell-style clamps which we love, if you haven't guessed by now.

The system had a pleasant grumble at idle, but nothing hinted at the sound it would make at wide-open throttle, where it had a beautiful roar. There was even a slight burble on deceleration, which sounded pretty mean.

The system made 168.32hp at peak and had a healthy gain over the stock system before the VGI (Variable Geometry Intake) switchover point - again proving that peak horsepower shouldn't be your only concern. Do us a favor; if you have a chance to peer at a dyno chart, look at everything else other than the peak number. Peak numbers are just for bragging; real gains show up everywhere else.

Freedom Design
Stock horsepower: 162.79
Stock torque: 170.16
Electrodyne horsepower: 166.14
Electrodyne torque: 176.67
Diameter: 2.25"
Price: $470.25
Contact info: Electrodyne, 703/823-0202, www.electrodyne.cc

Electrodyne's Freedom Design exhaust is one that proves what we stated earlier when we talked about error correction on the dyno. It is a rebranded Sebring system, as is the Remus system. The exhausts are exactly the same, down to the part number on the muffler, and the difference in power was within the 3% error correction factor.

The piping is coated with black high-temp muffler paint and looks nice, although it generates a lot of smoke when the engine is started for the first time after the installation. The system fits well, and even though the over-axle pipe is one-piece, it slides into place painlessly. The tips are a clean twin-oval setup, which looks really good peering out from under the rear valance.

It seems the reason the Electrodyne's output didn't match Autotech's is quite simple; it's a 2.25" pipe diameter, as compared to the 2.5" setup. The VR6 likes to breathe deeply, and the bigger diameter made a significant difference on some of the systems. This wasn't always the case, however, so we can't definitively tell you the 2.5 is a hands-down better purchase. But on average it makes more power.

GHL Motorsports
Stock horsepower: 162.79
Stock torque: 170.16
GHL horsepower: n/a
GHL torque: n/a
Diameter: 2.5"
Price: $689.00
Contact info: GHL Motorsports, 480/655-0935, www.ghlmotorsports.com

You may be wondering why we didn't print any dyno numbers for GHL, and that's because we received the wrong system. Turns out GHL's shipping department had accidentally sent us a 1.8T muffler. In the 1.8T, back pressure isn't a worry because the turbo provides plenty of it, so the muffler's internal design is different - although it's almost identical from the outside. That's why the problem wasn't spotted until after we fit the system and ran it on the dyno. The system was slightly down on power from what we'd expected, and it was the loudest of the group. The piercing whooshing sound suggested the system was too free-flowing and didn't provide the backpressure a VR6 demands. Since the exhaust wasn't suitable for test, we decided to withdraw it from the comparison, with GHL's agreement.

The GHL system is constructed from T-304 and T-321 stainless steel, and all the piping is mandrel-bent to provide the best airflow possible. It's supplied in three pieces with a separate reducer, similar to the EvoMS piece. The TIG welds and polished finish were the prettiest of the bunch, and the multipiece design allows for easy installation and adjustment. The kit includes everything you'd need to assemble it in your driveway.

We'll be sure to get our hands on a proper VR6 system in the future to see what it's capable of.

Jetex
Stock horsepower: 162.79
Stock torque: 170.16
Jetex horsepower: 171.34
Jetex torque: 182.11
Diameter: 2.5"
Price: $499.00
Contact info: New Dimensions, 408/980-1691, www.newdimensions.com

New Dimensions is the exclusive distributor of Jetex in North America, and although it's relatively unheard of, this system put down the largest power numbers. Admittedly, it didn't win by much, but it made impressive power below the curve as well as at peak. At 3,250rpm, the system produced 182.11 lb-ft of torque, which should break traction in first gear.

The system is constructed from stain-less steel mixed with nickel and titanium to avoid the problems that can develop when welding stainless steel, all the while retaining stainless steel's corrosive resistance. The metal mixture also serves to reduce resonance from the exhaust, making it quieter than most of the competition - until you run it through the gears, that is. The sound of the exhaust at wide-open throttle was excellent, and the low-key grumble at idle should keep the cops off your back.

The system also has a substantially lower price than the majority of systems in our test, so it offers a good bang for the buck. Jetex manufactures a reducer that slips onto the cat in a different manner than other products. Instead of a regular reducer, Jetex has a sleeve with cuts that slides into the factory assembly and are pinched down inside before sliding the mid-pipe over it. The system did prove to be slightly harder to install than the others, but the result was worth it.

Magnaflow PeformanceStock horsepower: 162.79Stock torque: 170.16Magnaflow horsepower: 171.15Magnaflow torque: 182.97Diameter: 2.25"Price: $547.05Contact info: Magnaflow Performance, www.magnaflow.com, 800/824-8664

The Magnaflow exhaust proved to be the exception to our rule. We were positive all the 2.25" systems would make less power than the 2.5s, but Magnaflow proved us wrong. This 2.25" system put down an impressive 171.15hp, placing it second overall for output. It also showed the highest torque number of the day with 182.97 lb-ft. Admittedly, it was only best by a hair, but remember it's a 2.25".

The system is constructed from T-304 stainless steel with a highly polished finish, and all gaskets are included in the kit. Installation was simple since Magnaflow uses a two-bolt flange connection instead of slip fittings like the majority of companies. This enables you to hang the system and then tighten everything up, but you'll need to get handy with box wrenches.

The one problem we had was getting the tailpipes to sit level. This was cured by adjusting the over-axle pipe. It took less than five minutes to get it right, so it was hardly an issue.

NeuspeedStock horsepower: 162.83Stock torque: 171.95Neuspeed horsepower: 168.02Neuspeed torque: 179.30Diameter: 2.36"Price: $679.95Contact info: Neuspeed, 800/423-3623, www.neuspeed.com

Contrary to what some internet trolls may say, we don't have a deal with the devil to only speak good about Neuspeed products. That said, Neuspeed's exhaust is a quality item that uses T-304 stainless steel, mandrel bends and TIG welds in a polished package. In fact, the only real complaint we have is with the DTM tips, which are a bit old skool now. In the company's defense, it does offer other tips if you'd prefer, but you'll need to upgrade to a 2001.5 rear valance in order to take advantage of them. It's also the only system that doesn't fit either the 2.25" or 2.5" category; rather it measures 2.36" or 60mm.

The system is a two-piece ensemble with simple flanges to attach the center pipe to the rear. The tips pretty much center themselves, and as an added bonus, we discovered Neuspeed had included a set of its polyurethane muffler hangers with the exhaust, eliminating almost all movement.

The exhaust exuded the traditional deep and loud VR6 tone, but since the system is guaranteed to pass any sound regulation in the USA, we weren't worried.

The final numbers were 168.02hp and 179.30 lb-ft - good numbers for this size of piping.

Remus USAStock horsepower: 162.83Stock torque: 171.95Remus horsepower: 165.41Remus torque: 174.49Diameter: 2.25"Price: $527.22Contact info: Remus USA, 818/882-6422 www.remus-usa.com

Similar to the Electrodyne exhaust, this system is a rebranded Sebring unit, meaning the only real difference we could find was the etching on the tips. Either way, the Remus exhaust looked substantial and possibly tied for the heaviest system in the test.

On the dyno, we learned why not many companies paint their exhausts: The ensuing smoke screen could stop a charging elephant. The tone of the muffler was nice and deep, while the power it made was almost identical to the other Sebring manufactured exhaust - go figure. Producing 165.41whp, which is less than 1hp off of some of its 2.25" brethren, this exhaust again proved pipe diameter plays an important role when it comes to producing VR6 power.

SupersprintStock horsepower: 162.83Stock torque: 171.95Supersprint horsepower: 169.36Supersprint torque: 180.84Diameter: 2.25"Price: $667.25Contact info: Supersprint, 800/239-7232, www.supersprintna.com

When it comes to top-notch exhaust systems, Supersprint is near the top of the list. We're not saying it's a favorite of ours, but we've seen what it can do on newer and older cars, including our project Scirocco. And while it can cost more than other exhausts, Supersprint has proven to be money well spent. As such, when we cracked open the packaging, we were again pleased with the welding and muffler, which featured oval tips introduced to the USA last year.

Installing the two-piece system was a breeze, with everything bolting together with little swearing involved. While the tips initially seemed large, we soon discovered they suited the GTI, and though some of us have an aversion to very shiny tips, these actually looked good on the black car.

With the car strapped to the dyno, the exhaust put down a nice-sounding 169.36whp, which placed it in the company of 2.5" exhausts. The torque stood firm, with the unit producing 180.84 lb-ft of torque to the wheels.

Techtonics Tuning Stock horsepower: 162.83Stock torque: 171.95Techtonics horsepower: 170.28Techtonics torque: 181.10Diameter: 2.5"Price: $360.00Contact info: Techtonics Tuning, 503/843-2700, www.techtonicstuning.com

There are a few companies out there that take real pride in their exhausts, and Techtonics Tuning is one of them. No matter what VW you have - even if it's a Mk2 with a VR6 swap - chances are Techtonics has an application for you.

For this test, Techtonics didn't send its most expensive 2.5" stainless steel unit, but its aluminized 2.5" exhaust instead, which utilizes a black Flowmaster muffler. The Techtonics unit also included hangers that double as pipe clamps. While seemingly more involved, fitting was actually so straightforward that we never skipped a beat.

Unlike almost every other system we tested, Techtonics was far from flashy. It looked like it meant business. Even the tip, which was simply a piece of tubing clamped to the muffler, didn't overwhelm.

Once the three dyno pulls were completed, the exhaust told us a different story. Rather than spending money on the packaging, it was obvious Techtonics' cash went into flow design, as the system's 170.28whp and 181.10 lb-ft of torque meant this bland-looking pile of pipes was only 1.06 horses off the top system.

Thermal Research & DevelopmentStock horsepower: 162.83Stock torque: 171.95Thermal horsepower: 165.74Thermal torque: 170.34Diameter: 2.25"Price: $585.95Contact info: Thermal Research & Development, 661/723-2872, www.thermalrd.com

Thermal Research & Development is a company we're familiar with after it helped us pull some extra ponies from our Mk3 project Jetta GLX. So we were keen to see how much power the Thermal exhaust would free from the Mk4 VR6 12v. The construction is similar to the one on our old project car - using 2.25" tubing, smooth bends, a shiny muffler and sparkly tips.

Installing the two-piece unit was straightforward. It used a flange and a gasket as opposed to a clamp-down setup, making the unit a breeze to mount. Sliding the muffler and piping over the rear beam required a little fidgeting, but nothing a couple of monkeys couldn't figure out.

The power output of this piece was 165.74hp and 170.34 lb-ft to the wheels, which put Thermal's exhaust on par with many of the 2.25" units. As expected, the sound was very nice. The car revved to redline without breaking our eardrums (possibly thanks to the center resonator).

The Results VR6 Exhausts Power Ease of Fitting Finish Price Pipe
Size Total Autotech Sport Tuning 7 5 5 5 2.5"
22 Euro Sport Accessories 7 5 5 6 2.5"
23 Evolution Motorsports 5 5 6 5 2.5"
21 Freedom Design 4 4 5 7 2.25" 20 Jetex 9 5 5 7 2.5"
26 Magnaflow Performance 8 6 6 6 2.25"
26 Neuspeed 5 5 5 5 2.36" 20 Remus USA 3 4 5 6 2.25"
18 Supersprint 6 5 6 5 2.25" 22 Techtonics Tuning 7 5 5 8 2.5" 25 Thermal Research
& Development 3 6 6 6 2.25" 21