There is about 1 instance on this site of an aftermarket cat working properly and not throwing a CEL. It sucks, I know, my aftermarket cat throws one constantly. I bought a wayne angle block, I haven't installed it yet, but I'm hoping that will keep the CEL off. What year is your ti? When do you need to have the car emissions tested? __________________ ~Dave~ 98 328ti Morea Grun slicktop 11 128i space gray slicktop 13 JGC WK2 Deep Cherry Search | RealOEM |