Supposedly cutting out the cat give you more hsp but cut some of your torque. I can understand why some people do it, but I still think that when you speed away from me, I don't wan a nasty smell. Don't you think there's enough pollution, we don't need more, and that's what the cat is for. Unless you are seriously close to be super fast just by a nice sounding exhaust and a high flow cat vs. getting a huge fine. Always better to go safe than stupid.