test pipe to high flow cat can vary from what i have read... if a high flow is that as you buy it say like thermal's, look for like 3-5 i think and if you whack out all the crap in your stock cat (ghetto high flow) its like 1-3. test pipe is like 5-10 as stated. theres a lot of info about this on the web, just look around :up: :up: