i ahd spoekn with my "good" mechanic today and he mentioned just to put a high flow cat on and a defouler so the CEL will go away, which is the cheapest thing to do. i have the DC 4-1 header on my car and was told years ago that that would eat up o2 sensors. i do not have emissions but im sure it will be here soon. i would hate to keep running it if the cat was blocked for some reason cuz them im looking at a bigger problem. there are 85k miles on my motor and my girlfriend said not a bit of smoke came out of the tailpipe running up to redline through 3rd gear, not even the typical honda black smoke. i'm gonna look at the cat tomorrow and see if i see anything, but i have always wanted a highflow cat or test pipe and the defouler would make it where i can run it correctly b/c i hat my CEL, it drains my gas.