hey i cant pass emissions in CA, my Nox is over by 180, i have a new BMW factory O2 sensor, the car seems to have a new Cat and new factory muffler.
Also, maybe its just me, but my 525i doesnt have very much lowend power but has exceptional highend torque. my car sat for 5 months before i bought it, I've been driving it for 2 or 3 months already, but no improvment.
the orginal O2 was bad and I replaced it, could the old one have burnt up my Cat?