My guess would be so that customers don't come back with error codes for cats, EGR, Evap, ect. Unfortunately, it turns off important monitors (misfire monitor, EGR codes, ect) and will not allow you to pass inspection.
On the LSx platform, you just turn off the monitors you don't need by setting them to "ready" (cats, EGR [if deleted], AIR) and leave the monitors that still work to run normally, such as EVAP, Misfire monitor, ect. Thats the best of both worlds, because you can tune out the uneccessary monitors, leave the important ones, and still pass inspection without any problems!!
Perhaps someone can answer why this can't (or just isn't) done on our cars??
