Originally Posted By: Kestas
Though we have a few ricers, they don't dominate the scene as the RWD crowd. The one similarity, though, is that we love our cars.
No question about that, as well as the golden rule "there is no replacement for displacement" exists even in the ricer crowd.
Originally Posted By: TallPaul
EDIT: I think Panda Bear's post means that opening up the muffler won't hurt performance because the cat already provides sufficient back pressure for the way the engine was designed.
Anyway, the following explains my experience wiht just replacing muffler and tailpipe, and it made a noticible improvement for my F150--and sounds a ton better too (big block inline six 4.9L).
Stock mufflers can be very restrictive. MY F150 had something like 1 and 7/8 or less ID on third tube for a 2.25" system which had 2.125 ID. The Flowtech Raptor and a short side exit pipe made a discernable difference in power for my F150. I'll say the pipe from the cat to the muffler was fine, but the F150 had a crimped restrictive tailpipe that wound from here to kingdom-come around the axle etc to the back.
Beware not all "performance" mufflers are full diameter all the way through. I have looked down Cherry Bombs and they do restrict, as does Thrush Turbo. The Flowtech Raptor is full diameter through and through, cheap, and sounds great!
I can only speak from the Honda I've known, that they are already well tuned for the typical power band the engine is designed for. The diameter is the same from the exhaust port of the engine to the tip of the muffler, stock. Modifying such a system will only "shift" the power band and raise the peak for a small amount (less than 3 hp for exhaust, 10 hp for the entire intake/header/cat/muffler, sometimes even make it slower if the system is too big), and would rarely make a car noticeably faster without changing the transmission gear ratio, cam profile, and the fuel/ignition map at the same time.