mufflers

I think an X-pipe w/ a flowthrough muffler is about the closest you're gonna get without swapping to one of those engines. Its not completely the exhaust system that gives those cars the sexy exhaust note.

[ame="http://www.youtube.com/watch?v=i-gLzKRgIoQ&feature=related"]YouTube- 71 Chevelle / Pypes true duals w 3"X-pipe & Race Pro Mufflers[/ame]

If you wanna go extreme(without spending a ton for an exotic motor) to get that sound, your best bet will be a lexus V8.
[ame="http://www.youtube.com/watch?v=QtgoFrDGBFE&feature=related"]YouTube- Lexus V8 Powered AE86 Corolla[/ame]

but who wants to go through that much hassle for an engine that doesnt have a ton of aftermarket? and will have half the people on this site calling you unamarican(misspelled for annunciation purposes