Originally Posted by Mike Lu
it won't trigger the CEL (increase emission) as long as you keep factory primary cat intact, hence, your situation (cat-back exhaust), you won't need to worry about the emission. As for the smell, same story, if you leave your primary cat alone, it won't be too bad except the first heating cat cycle of the cold start.
Well, what I'm thinking about doing is getting Borla Mid pipes and the Remus Race axle back exhaust. So, lets hope so! Not to mention my catless downpipe.