I have a Buschur 3" DP, Perrin 3" HiFlow Cat, and a Blitz 80mm Catback. I have other mods with are listed in my signature. I had the car dyno tuned about a year ago and everything is running great with the tune. For the past few months I've been getting a check engine light off and on but now it's been on. I went to my friend's shop so he could check what code triggered the light. He said it was the Cat or O2 sensor. What can I do to rectify the problem? I've heard of using spacers on the O2 or the O2 Simulator... idk Someone give me advice please...