I have a 2009 Scion tC with a Megan Cat Back Exhaust, and an AEM Cold Air Intake I'm wondering how much horsepower I can get it up to while not risking breaking it, it's a 5 speed and I feel like it should be going faster than it does.

 

For tCs bolt-ons don't really do much. Your best bet at making power is boost. Don't waste money on bolt-ons and expect significant gains.