I have a pair of PYPES cats for forced induction motors that may go in my exhaust system, not sure how good the mains are. The rears will be removed when I get Rob's headers. I would think a good muffler shop can swap in most cats by adding some length or cutting more out to start with depending on the length of the new cats. When these cats were removed the guy who took them off had moved them way off to the side but I found them. They have less than 2k miles on them. I paid $300. for the pair from Summit or Jegs.