A gross polluter usually is the cat. I wouldn't put anything by it. It obviously is not working at all. Most muffler shops carry factory re-man. cats. My bro just had one put on his gross polluting 96 rs (intake only) and then it passed w/flying colors. Not sure when obd-2 started? or what his may have been, but that is what he did. Cost about 3 bills installed.