let me jump in and see if I can also get some help here, so I just bought a V6 mustang from florida and it has no cats. its got a built motor had a turbo on at some point, but its back to N/A now, so its was tuned down south and its not trowing any codes. Im in process of registering the car this coming week and then inspected , should pass it even tough the cats are not there?
If the mechanic notices the cats missing he can fail it. Putting in a set of high flow cats will avoid the problem and is good for the environment ($160 for a pair from American Muscle). Good for the environment? Drive behind a school bus lately? I have to shut the outside vent in my car when I get behind school buses because of the fumes.
Back to your question. If you have the mil-eliminators the computer thinks the cats are there, so no code, mechanic has to see they are physically missing. I don't know if the computer/diagnostic that DMV uses for the inspection can detect if they were turned off in the PCM with a hand held programmer. Mustangted chimed in earlier in this post stating if they are off via a hand held programmer it's a fail.
I just did some web surfing on the subject of OBDII testing protocols and I see it is possible that DMVs computer can check your PCM if it is performing a readiness test of the o2 sensors. So if you had them disabled by a handheld programmer it is possible to fail emissions. Let me check with a friend who does inspections to see if he knows anything more.