I'll bet you can end this thread really fast with two questions:
1.)What is the OP's budget?
2.)What is the OP wanting out of the system? (ie, sound, looks, "bang for the buck," etc...)
If the budget is only $400 then that really eliminates a bunch out there.....
If it's $600, then that opens up some doors....
If it's $900, then there are only a couple that might not fit in that budget.
Best Catback (money no object)
Corsa or LG
Cheapest Catback
Cherry Bomb
Everything else falls in between those 3.
Ivan