Your rear O2 sensors need to be turned off. It is a commonly known fact that long tube headers paired with high flow cats can cause issues keeping all four O2 sensors on and require extensive tuning to achieve that stability or the just simply need to be turned off. If you have an off road mid pipe, all bets are off. Your rear O2 sensors need to be turned off and stay turned off. They are technically also for racing use only. "49 states legal" is a laughable on all levels.