I recently got a check engine light, scanned it and got a "Catalytic Efficiency below threshold (Bank 1)" So, I tried new O2 sensors, that wasnt it, and I replaced the Cat with http://www.autopartswarehouse.com/ap...003&modelid=65 , the first one. However, I still get a CEL with the same code. So, right now it has 2 new O2 sensors, and a new Cat. Previously the MAF sensor hose was slightly off, but I fixed that and everything is fine with it. Im not sure what to do about this. Ive heard that you cant put aftermarket catalytic converters on, but ive also heard that it will work just fine. Any help would be appreciated, also, where can I get a stock Cat, that wont cost me 800 bucks, should I need to replace it AGAIN!