Replacement cats for kooks x pipe??

Bought a set of kooks long tubes from a guy who blew a hole in his block headers are in perfect shape. the catted x pipe that comes with the headers well not so good im guessing a valve went threw the driver side and threw the cat so its pretty much gutted. Anyone know where to buy just replacement cats?
 
Pypes and Magnaflow are two I've seen. They run $80- $90 each. I would call and make sure they will not cause a problem running two different cats if you're thinking of just replacing one.