99 Integra LS - high flow cat converter

I've been fighting this problem for about 4 months now and i went through all kinds of options.

I installed a high-flow cat converter, so obviously the post cat sensor is going to complain about the emissions. I got a O2 simulator for it after weeks and weeks of research and painful switches, and that gave me a P0138 High Volts error code. I tried a different one that was guaranteed not to go over 9V in output and that one gives me the same error code still.

I talked to the person that builds them, and he custom built an adjustable simulator with 3 adjustments: High Volts, Low Volts and Frequency. I tried adjusting these 3 (one at a time - in one step increments) nothing worked. I'm still getting a P0138 high-volts error code.

The person that makes them researched this and said that some Mazda's at least are testing for this by looking for the signal to be above 0.45v (in the normal rich voltage) for more then 6 seconds during deceleration. This would mean that our output levels are fine, 0v to 0.86V, but our frequency must be adjusted faster so that the simulator LED stays lit for say 3 to 5 seconds.

Does anyone have any history with these issues? Anyone that can give me some type of clue as to how to get that light to stay off, i would be eternally grateful. Is the post cat snooping on the values of the precat?
Why does the high-volts eror code keep popping up?

thank you so much