If you want to go with the 2.25in, Maganflow has a catback that uses that size pipe. it comes with a resonator and you can get either a single or dual exhaust. I have the dual on my 4 cyl and love how they sound. they are deep when you get going but once you get to cruse speed they sound like they are not even there.
note: its kinda hard to get the sound of the WRX.


check out my sound clips below to hear and see