If you want some good sound use 40 series flowmasters with an x-pipe. Dynomax 2-chambers aer sweet too. As long as your not running a ridiculous size pipe like 3.5" pipe you shuoldn't lose any back pressure. 3" is pushing it for a SBC. If you ran 3" with an H-Pipe to equalize the exhaust pressure with 2 chamber mufflers on it'll sound... sweet.

Good Luck

Jon