importeater

Did a search and only came up with things like "should I use a new O2 or a Sim" nothing stating how they work. I have emissions but its only a plug into the computer and not a sniffer.. Will the sim pass me if I chose to gut my cats or go with a bigger cam, ext...?

TIA
Craig

GREGG 97Z

O2 simms replace the rear two O2 sensors on dual cat OBDII cars. Your car has four O2 sensors, the front two monitor the A/F ratio and effect engine performance, the rear two are after the cats and just monitor if the cats are functioning properly. The only reason you would need them is if you gutted your cat or when installing single cat shorties or LT headers since they have no place to mount the rear O2's. I don't recomend gutting your cats, you will see little to no performance increase from it and you probably wont like the sound of the exhaust without them. If you have to do a sniffer test there is no way you'd pass without them, no sure about just the plug in test.

importeater

Yea I wouldnt gut my cats just was using it as an example. Thanks for the info..

Craig

AxeGrinder30thZ

I just bought a pair of O2 sims...should come in the mail any day now. I cut my cats off a while back. I love the sound of it. I didn't really do it for a performance gain. I just wanted it louder.