i'm getting ready to put exhaust on my 67 camaro. I have 454 . will 3inch or 2 1/2 inch exhaust work better. this is a street/strip car. thanks dave

3"

with what a flowmaster or a magnaflow and with a h pipe or crosspipe

What size is your engine ? 3" is overkill for many applications. It can also be difficult fitting 2 - 3" pipes under the car.

its a 454 with a 830holey, a 540 lift, roller motor, th400 , rpm air gap, msd ignition