My cat was broken inside and blocking flow as well. I took mine out and just hollowed it. I didn't find the need to waste money on a part I didn't want to buy because I plan on getting a Random Tech. cat but didnt have 300 bucks to spring at the time. Since I had problems with mine I noticed a differance on how it ran and certainly had noticable more power. But as I said, it was suffering before. My CEL comes on about once a week and I just clear it at work with our scanner. After seeing the honeycomb I cant imagine how one would plug up with out some kind of engine problem. If you are just wanting to try something new I don't know if I would waste my time. Keep the cat and everything the way it's supposed to be. If you have a problem and don't mind a cel then swap it out. My milage was down from 27 ish to squeakin out 20-22 with out changing driving habits. If you have a problem you'll know.

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