I'm running around catless and had been throwing CEL's for a non-functioning cat (DUH!!). The car seemed to be driving worse, so before i bought a high flow cat to be welded onto my test pipe i decided to try an O2 extender. I installed the extender along with disconnecting the battery(reset ecu). I ran it through the 3 duty cycles and no CEL, the car also drives alot better. I guess reseting the ECU should be done after every mod. I didn't do it after i installed my Turbo XS Hybrid BOV and now its doing alot better(no pops or backfires).
