Originally Posted by bmwm3redblack
So HP gains don't depend on size?
Power comes from the removal of the cats. Look at the turbos when you remove your downpipes and you'll realize where the real bottleneck on the exhaust side of the system is.
I ran 1/4 miles with 3" and 2.5" downpipes back to back multiple times and could not pickup any difference whatsoever. The times were always identical between the two.