I bought a "high-flow-cat" off EBAY for like $35 shipped or so. it has been a couple of months n-e-ways. i got 2 1/2" piping ran from cat back and at first it sounded ok. come to find out it was just a resinator and it didn't do shit but fall apart. last night i put the stock cat back on after i cleaned the guts with carb cleaner, and man the car really runs great now. i can really hear the kick in my vtec and it feels like a new car. so the saying stands "you get what you pay for" so i suggest that if you are going to replace your cat, spend $100 on a real high flow cat.