If you want the best for the scion tc, then go with the
HKS Hi-Power Exhaust - Sound exhaust but improves performance
(sound clip)
http://www.youtube.com/watch?v=QZvdkr3S5P4 (w/ the Injen CAI.
Greddy Turbo-back Exhaust -Main Key, performance, then sound
(sound clip)
http://www.youtube.com/watch?v=_upWMXPaujE
have anymore questions, just pm me. I DO my homework