So do they run it on the rollers or just plug into the OBD-2 port? In WI, they only plug into the OBD-2 port. As long as the car's PCM is happy, you pass with flying colors.
Is your check engine light on after gutting the cat? I'm guessing so.
You have two options to make your PCM happy. Replace your gutted cat/bad flex, with one from your local junkyard. Your other option is to get a
MIL eliminator. The MIL eliminator will only work if there is NO visual inspection. If the DMV sees that your bypassing the emissions systems, it could mean fines.
HTH,
BP