If you are looking for NO drone, go with a stock WRX catback. Anything aftermarket is gonna have some sort of drone on our cars..
I have an SPT catback, a lot of guys have stock WRX, Nameless, Magnaflow, etc.. List goes on and on.. It all basically comes down to what you think looks the best.
I recommend starting from the beginning of the ('08-'10) 2.5i thread...