flowmasters flow well and sound damn good. They have an agressive loud tone at all rpm.
Cons- Everyone has them, its 40 more for the name, loud nomater what = cops dont like you, the rough noise isnt for everyone.
Dynomax Turbo flows actually flow somewhat better, and sound much smother, they run 40 each, but they are not as loud.
Borla, bitchen sound, awesome flow, overall best, but about 150+ a muffler.
For your 6 a flowmaster would be good, would mimic a 350, eventhough you have a 3.8 I heard flowbies on a 3.8 Firebird, sounded really nice.