hey guys thanks for all the suggestions. This is what i plan on doing to the car, i'm going to start making a homemade turbo kit, and in a couple of months when i have all the parts put it on. But right now i have like 105k miles on it and i was thinking that it might be time for a new cat., so i was either going to buy a high flow cat. or a test pipe. The test pipe i was looking at as a bungle for the o2 sensor. So with that said test pipe or high flow cat?