[turbotko]

As far as the CEL goes for catalyst efficiency your gonna get that sooner or later if you delete the primary cats. The reason for the post cat 02 sensors is to do just that, check for properly operating cats on the car. I'm sure a competent tuner could tune the catalyst monitor out of the DME, but I'm not sure if it could be done with a piggy back.

The post cat 02 sensors are there due to OBD regulations. The catalyst monitor fault will most likely be stored in the DME very soon after driving the car the first time without cats, but the CEL will not come on until the DME sees the problem in 2 or more consecutive drive cycles. It has alot to do with how it's driven as a OBD2 drive cycle has some pretty weird conditions. I used to go 6 months at a time without catalyst monitor faults being stored in my cobra but that was because I drove the crap out of it everywhere I went. One road trip down the highway was what normally set it.

The post cat sensors are bosch LSF 4.2 sensors with a normal .1-1.0V range. It would be my guess that some regular old O2 sensor simulators might do the trick in eliminating the cat efficiency fault.