To replace catalytic converter--Yeah or Nah??

My muffler and exhaust piping are on their last legs due to living in the "salt belt" and I am debating between getting a stainless steel system (borla or gibson) or going with the aluminum Calmini AND a high flow cat. converter here: h igh flow cat. converter . Any opinions?? or should I just go all out and get the stainless steel system AND the high flow cat??

You do realize the main cats are alongside the engine right? The post-cats are the ones down below that have the kink to turn horizontal and would be exposed to salt and such.