I PERSONALLY think that 2.5 is pathetic. That's GREAT for a Saturn 1.9L (ok...so 2.25 daily driven, but 2.5 is great for the ones that see more "abuse").
On a V8...that small? Come on now, UP THE SIZE. You want HIGH exhaust gas velocity (and high volume transfer), and as little backpressure as possible. No matter what you all think, backpressure chokes an engine. It's one of the myths everybody believes, like open headers burning valves and aligators in New York's sewers.
My down pipe (stock) is about 2". GM (for some DAMNED REASON) decided to reduce that to 1 7/8 at the end of the cat. They then decided to take that down to 1 1/2 at the muffler.
Go talk to some local shops, you'll be suprised what they can do. You'll definately be happier with bigger than 2.5. That V8 won't really suffer from low end torque loss (pipe DIA's alter the power curve and move it higher in the RPM band. Although this may sound crappy for street motors, they also rev up to those peaks much faster).
Toss on some straight pipes if you can. They sound SAWEET on 302's.
the time and money u waste tring to uprgrade the size of the pipe your better off stickin with a bolt on cat back system... they designed em that way for a reason.... on a 5.0 there really is no reason u need to get bigger than 2 1/2 inch pipe on it..
Exhaust
