PSA to V6 owners for exhaust mods
I’m now swapping to a 302 motor and thought I should show what I run for my V6 exhaust before I toss it. At pretty much every autocross event or car meet I’ve brought my car to, every new person I meet seems to think my car is a GT, so it works for some people. The main thing, though, is that it just doesn’t sound like hot garbage, so I figured I’d show you how I run mine. (I don’t have any sound clips, sorry.)
This is the fourth exhaust system I’ve made for this car, and I’ve even developed harmonic calculators for college using it.
A few big things about the fundamentals of the harmonics on this car: a V6 fundamentally resonates at 3500 and 5500 rpm, which is generally where these cars sound like hot ass. You need resonators tuned for those specific bands. Luckily for you all, that’s why these cars come with four catalytic converters. The two 5-inch pre-cats are tuned for 5500, and the 14-inch main cats are tuned for 3500.
If you crack those cats open, you’ll find that they’re decently high-flowing. The main 14-inch cat only has about 20% that is actually a catalytic converter—the rest is an echo chamber to help stop resonating. I know it’s popular to go catless, but I would highly recommend against it. You won’t gain any power. The only change I made was deleting one of the 14-inch cats and combining both cylinder banks into a single 14-inch cat to help stabilize the exhaust pulse. (Y-pipes also give you a torque boost on V6s if you do it right.)
My entire system is 2.5 inches from the collector of the headers to the tailpipes. As you can see in the photo, the whole system is not a real X-pipe—you don’t want that anyway. You want the two pulses to combine into a single smooth one, then split again into Super 40s to the tips after that. The 3.8s have one really big thing going for them: they are 90-degree V6s, so they have a very harsh and deep tone. You need to take advantage of that while keeping it from resonating. This system works very well until the very high end, but even then it still sounds pretty damn good for most of the range.
Also exhaust leaks are persistent on these cars, I replaced all my donut collectors with V-band clamps and flex pipes
Any questions, feel free to reach out!