what is the diameter of the factory mid pipe on a 98 3.8? from the cat to the muffler, is is 2 1/4"? i was thinking of making a new intermediate pipe for Darlingreject's car, and debating to go with 2.5, 2.75, or 3" pipe. its already got a ported and polished intake, comp cam gt1 cam, pacesetter headers, pcm tune, magnaflow muffler, and will have the cat removed at that time as well. later on it will be built for turbo and really only wanted to make the pipe once if needed.

 

My friend has a 3.8 Firebird and I think his car has the 2.5" pipe. He upped it to a 3" and has the Flowmaster dual outlet muffler on it. I will warn you though, it will sound RASPY!!! He had to put a glasspack between the catalytic converter and the muffler to get rid of the raspy over tones. The glasspack made ALL the difference. It sounds so beastly. It made it sound soooo smooth like the Magnaflow commercials you see on speed tv lol. Almost as sexy as true dual exhaust. 3" piping will help it breath too Do it! lol

 

2.25" is the ID I believe.

 

alright, thats. ill go with the 3". i have heard the flowmasters in general and they are very raspy, as is the off the shelf magnaflow v6 cat back. we can try this and if its got some rasp ill add a resonator to tune it out

 

It will sound so sweet and smooth if you do the resonator because it has the aftermarket cam. Mmmm that would sound sexy