^^ What they said basically.
If you're not anal about using American stuff. Edelbrock make some of the BEST sounding mufflers I've ever heard. $250 a pop but sound incredible on any car I've ever heard them fitted too. (Yes seen a WRX with one too!)
Magnaflow also make some really good stuff.
On a local market, I wouldn't go past pacemaker, their mufflers are also very good, But I'm unsure as to whether or not they will fit under a lib. (Anything can be made to fit, some easier then others, I'm not sure if Pacemaker will make a muffler to the right shape, but it could be worth looking into.)
I didn't say what I said to be a controversial prick (this time

), It is my genuine opinion after having lived with a POS exhaust system for 12months or more.