Recently installed greens I had laying around since I was replacing the intake manifold gasket anyway.
Getting a rich code now (obviously) as well as an intermittent rear O2 fault. Which doesn't make sense since I bought the "tune" when I was already catless. Figured that would have been completely coded out.
The rich code is obviously because your front O2 is still functioning (it shoud be!) and the greens put more fuel out per millisecond of activation. Coding out the rear O2 is much more work than disabling the setting of the DTC for a catalist efficiency, which in all likelyhood is what was done on your tune. This obviously requires the rear O2 to still be physically in the car and electricly connected up and functioning. The DTC you are getting is related to the rear O2 having intermittent connectivity problems or actually malfunctioning. I wouldn't bother myself to try and code it out and just replace the rear O2 sensor and check the connectivity.