I will be doin a stage 2 turbo on my 03 ecotec and a custom exhaust what size exhaust would you use 2.25? 2.5? or 3? or should i go a magnaflow exhaust or something like that? Give me your opinion on both please thanks!
With a turbo its best to have the lowest amount of back presure after the turbo. At least thats what I have been told if its different someone please correct me. Now I don't have a turbo but I am wait for the supercharger kit to come out so I had 2 1/2 inch put on so
when I get it the exhaust is ready. 2 1/2 was kinda tight i don't know how 3 would fit under the car.
Semper Fi SAINT. May you rest in peace.
2.25 would allow the turbo to spool quicker but I believe it may limit the maximum pressure (boost) after a certain point. I don't know how much boost you plan on running or if you plan on intercooling it, but I'd say at least 2.5". If you go 3.0" you might lose a ton of low end power and it will take longer for the turbo to spool but you would be able to see more max boost. I'd personally run a 3" downpipe from the turbo and then reduce it into a nice 2.5" catless exhaust system with a low back pressure muffler. And get a good muffler not one of those gay oval shaped ricer mufflers. I'm talking about a borla or magnaflow or even a flowmaster.
If you feel like you need more than 2.5" at a later date when you want to turn it up more, then you could put a cut out on down pipe where its still 3". I have seen some vacuum operated ones that open at a certain pressure, say 10 psi, and when its open you bypass the entire 2.5" system.
Just remember 2.5" is a big pipe for a 4-cyl engine.
What kind of turbo and intercooler are you going to get? Have you upgraded your fuel system yet? I personally wouldn't run any boost on a stock fuel pump and injectors. Even if some guys here are doing it, you'd be surprised how lean there enging can get up in the higher rpms when running boost because the injectors hit 100% duty cycle. Its not good. The best thing to do would be to put the car on a dyno w/ a wideband O2 sensor and tune it before you go around putting your foot to the floor on the street. Better safe than sorry. Know what I mean.
I just saw a turbo eco over the weekend in Chicago and it was pretty sweet. Guy was running 12.80 in the quarter with like 1.9 or 2.0 60 ft. times. If he could get it down to 1.7 or 1.6 he'd have a low 12 second car.
Best of luck to you.
Scott
2002 Audi S4, black
1996 Z24 auto, red
