spintech

65 Dart: I'm running 3" high-flow cats, an X-pipe, and exiting out the back. It sounds pretty deep at idle and really roars when you want it to. Their website has a lot of youtube links of sound clips (if you click on one, it links you to 15 more). My Sportsman XL's sound a lot like the white Mustang LX on their web site, only deeper.

http://www.spintechmufflers.com/spintech/spintechindex.asp