I'm surprised that nobody mentioned pypes exhaust. they don't make headers for our cars, but they make everything from the mid-pipe back. they have sound clips on there of a 2002 GT and it sounds bad-ass :hitit:
check them out www.pypesexhaust.com imp:
i had a flowmaster catback and the 2000-3000 rpm drone annoyed the shit out of me. now i have the mac h pipe and catback and it sounds great. better the my friends mustang with magnaflow side exhaust IMO.
I have the flowmaster american thunder system on my 96 GT with a BBK catted h-pipe and love the sound of it. Everyone has different taste though. I've also heard a lot of good things about the magnaflows too.