By Travis Thompson
I recently got the itch to start modifying my Talon, but was disappointed with how little dyno-test data was out there. There are plenty of highly modified DSM cars out there, and their owners are happy to tell you what their cars run in the quarter mile and what kind of power they make on the dyno. But between these fully built cars and stock, there isn’t much quality information out there.
The structure of this before and after dyno test is simple: dyno test the car (the before), install a 3-inch exhaust system (and change nothing else), dyno test the car (the after), and finally, share the results. This will show us exactly how much power the car picked by switching from a stock exhaust to a full 3-inch system. Of course, your results may vary slightly or greatly, depending on what other parts you have. One reason it’s hard to find dyno-test data on any single performance modification is that many owners make the leap and upgrade the wimpy stock T-25 turbo, intercooler, and fuel system at the same time, making it hard to pin down where gains came from. If you already have a bigger turbo, you’d probably pick up even more power from this exhaust upgrade.
The test subject is a mildy modified all-wheel-drive 1996 Eagle Talon TSI. The car currently has a manual boost controller, a hard intake pipe with an open-element air filter, hard upper and lower intercooler pipes, and a GReddy blowoff valve. The turbo, intercooler, and entire exhaust system are stock. I drove the Talon to DB Performance for this test because they have an AWD Dyno Dynamics dyno. Dan and Shane ran a handful of pulls on the dyno, and each varied by 2 or 3 horsepower and ft-lbs of torque. After a few runs, the intercooler and piping definitely got hotter and the car started to lose power. On the best run, the Talon made 152 horsepower and 167 ft-lbs of torque to the wheels. The boost almost hit 15 psi from about 2,800 to 3,000 rpm, held about 14 psi to about 4,300, and fell down to 10 psi by about 6,000 rpm. The stock tune was incredibly rich, mainting an air/fuel ratio between 10 and 11:1 throughout.
The new exhaust system consists of a bunch of parts I pieced together as cheaply as possible. The system begins with a 3-inch stainless steel Megan Racing downpipe. Truth be told, the pipe starts at 2-3/4 inch and expands quickly to 3 inches right behind the front flange. Some downpipes have sections at the front and rear that neck down to 2-1/2 inches, so make sure you know what you’re getting when choose a downpipe. I had Andy at DB weld a 3-inch Magnaflow catalytic converter into the downpipe. The cat back consisted of a VRS exhaust 3-inch stainless piping kit and a Magnaflow muffler with a 3-inch inlet and dual 2-1/2-inch outlets. I chose this setup because I wanted it to look as close to stock as possible. I even wanted to reuse the stock tips to save money and keep it looking stock.
In retrospect, it may have been cheaper and easier to use a fully welded/assembled cat-back system, as the VRS piping kit required quite a bit of cutting and welding to get it to fit. I’m happy though, because the system looks and sounds exactly how I hoped. Only a trained eye can tell it apart from stock. The sound is aggressive but tasteful, and never gets that distorted or blatty sound that some setups do.
Back on the dyno at DB Performance, the upgraded Talon put down 168 horsepower and 183 ft-lbs of torque—a jump of 16 hoursepower and 16 ft-lbs of torque. With no changes to the boost controller, the boost peaked at 16 psi and held an extra psi throughout the RPM range. The air/fuel ratio also leaned out a little below 4,400 rpm.
With the stock exhaust, the Talon put down 152 horsepower and 168 ft-lbs of torque on the DB Performance all-wheel-drive Dyno Dynamics dyno. With the new exhaust, the car made 167 horsepower and 183 ft-lbs of torque to the wheels. The great thing about this upgrade is that it made more power all the way through the RPM range.
This dyno graph shows the boost level in relation to the RPM and horsepower numbers. With the freer flowing exhaust, the little T-25 makes an extra psi throughout the RPM range. It also spools to peak boost a little sooner.
Well there you have it. You can pick up some decent power with a 3-inch exhaust system, even with the tiny stock T-25 turbo. The new system even includes a catalytic converter, which some owners go without for extra flow and faster spool up. The next logical performance upgrade for this car would be a turbo that could hold that 16 psi (or more) all the way to redline, but then of course I’d need a way to tune it, and a front-mount intercooler, a fuel pump upgrade, and so on...
This pile of parts became my new exhaust system. It included a 3-inch stainless Megan Racing downpipe, 3-inch stainless VRS cat-back piping kit, 3-inch Magnaflow muffler and catalytic converter, and a ported O2-sensor housing, which we decided to save for another day.
The underside of this car is very corroded from the salty Minnesota roads. In this shot you can see how the factory downpipe bolts to the O2-sensor housing, as well as the factory flex joint. The downpipe is covered with a heat shield, making it look larger than it really is.
The huge factory cat could technically be unbolted, if you could get the bolts off. Notice the rear oxygen sensor and ground strap behind the cat.
The heavy factory exhaust features two resonators between the cat and the muffler. No wonder it’s so quiet and flows like crap.
Here’s the rest of the factory cat-back system. It looks like there’s plenty of clearance everywhere for a larger-diameter system. From this view, it looks like I’d have rust holes in the floorboards before the factory exhaust.
One of the ways I saved money was by purchasing the cat separate from the downpipe. Andy installed the downpipe and marked where the cat would go in permanent marker. Then he dropped the downpipe, cut it up, and welded in the cat.
The next step was to mock up the cat-back piping, including the hangers. Andy spot-welded everything into place.
The rear pipes and muffler are spot-welded into place. It took quite a little cutting and measuring to get the 3-inch pipe to clear the swaybar and for the muffler to be in the right position.
Andy dropped the cat-back and welded it on the ground. Compared to stock, the new 3-inch cat-back looks huge in diameter, plus it has fewer bends and resonators.
With the cat-back welded up, it was bolted back up and re-hung.
Notice how much tighter the clearance is between the rear swaybar and exhaust pipe. I didn’t really want to add a bigger swaybar anyway, did I?
With the system nearly finished, Dan polished up my factory exhaust tips and installed them onto the new muffler. The system will look almost stock, save for the polished muffler and the fact that it exits at a slight angle.
With everything finished up, Dan and Shane threw the car back on the dyno to see what kind of power it picked up. The new exhaust system netted us 16 horsepower and 16 ft-lbs of torque. Now the car is ready for whatever turbo and intercooler setup I throw at it.
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