CPE:
pros: one piece design, can have cat in it
cons: costs quite a bit more, couple people cats have went out...in which case you have send the whole DP back, and wait for them to send you a new one (they wont send you a new one, then you send the bad one back when you get it)
Corksport
Pro: Cheaper
Cons: two peice design (leaks?...mine doesnt leak), no Catted option
Performance should be virtually the same...Corksport utilizes divorsed setup which is supposed to be 'better'. You can always weld in a high flow cat into the corksport mid pipe (like me) and get a catted 3" exhaust system for still quite a bit cheaper than what CPE has.