You can help the rear O2 by either:
A) getting a pcm tune that doesn't care what the signal is from the sensor anymore (2001+ need to leave sensor plugged in, due to an extra test the car runs on itself every few miles... some advanced tuners can deal with this, but it's avoidable by leaving the sensor in-line)
B) use an O2 bung extender (basically spark plug anti-fouler), which sets the sensor a couple inches back from the main stream of the exhaust to sniff less hydrocarbons and be happier without usually needing a tune
Well it's official, P0422 popped up again last night. We are gonna go with a stock cat because we need it to pass emissions by next Friday. Thanks for all your help, maybe in the future will I actually put some upgrades on it. On an unrelated note, a high pitched whining noise that follows the RPM started today. My suspicion is the power steering pump as it's been starved once before and it sounded exactly like that. I'll be able to check tonight.
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