The car eggbeater has now passed Harris County (Houston) emissions easily (better than many newer cars I've seen) with the aussie DP and stock mid-cat, so gutting primary as has been said is unlikely to effect testing. It is highly illegal to tamper with a cat though. If you do it, do it at your own legal risk and make sure you don't include anyone in the activity that doesn't know the risks etc. Don't throw the material away in your parents or friends trashcan or at work etc. The EPA would have a field day, even though the risks of discovery are pretty small, be aware of what COULD happen.