Originally Posted by TrueWhiteBoy
Stage 2 with a stock DP - 1 gutted cat and 1 good one
Been running that setup for a couple years.
Failed recently. Passed everything but the startup
Likely cause is that over time the 2nd cat started breaking up.
the smog tech should have left your car running before he did the test......gotta keep the cats warm or they arent as effective at cleaning up the exhaust.