you will need two high flow cats if you plan to run cats. You can get them for about $70/ea. if you look around.
I got my flowmaster exhaust kit from Jegs. It is the force 2 system and you have to order the exhaust and the resonator seperately. Total cost me around $400 for the exhaust, plus $200 for custom catless downtubes at a shop. The guy didn't give me a receipt because of the liability of removing the cats. I really had to bug him to do it, he told me no at first. But after we talked a bit he finally agreed. I think he was just feeling me out to see if I was undercover trying to get him busted or fined.