2001 Impreza 2.5RS STM
I'd like to put a test pipe (cat delete) on my 01 rs, but I don't want to throw a CEL. What is the best way (that is easily reversable for emmissions) to do this. I've seen the o2 sensor bypasses that send a signal to the computer saying the cat is working right regardless of emissions, but do those cause any runability problems? Also there are the o2 sensor spacers that set the o2 sensor out of the direct stream of exhaust flow. Any others? Anyone used any of these products or have experience with test pipes?