I just spoke to a Flowmaster rep. and was told that I needed a 4.5 inch exhaust pipe on my 88 Trans Am. I was then informed that the only muffler that they offered was a race only version and that it will wake up the neighbors two blocks over. I can not seem to locate any company that offers that size pipe and a muffler to fit it. I know that there are people out there with third-gens that make more hp than 450 and I am looking for some advice on pipe size, routing, and mufflers for my car. Any help from you high horse power guys will help much. Thanks, Jeff P.

 

im running true dual 3" Flowmasters on my 88 IROC Convertible... 383 Supercharged.

 

It may be true that a 4-1/2" muffler is very hard to find (in a street usable one anyway), but you don't need it.

Mufflex made the exhaust for the Spohn car ad (97 convert LT1) and it runs in the low 9's with a 4" single (over 900hp), so it will work. I say go for the 4" of which streetable mufflers do exist. Call or visit Mufflex's web site and ask them-they are the experts.

FYI: I have the 3-1/2 exhaust on my 390hp 350, it works pretty damn good.