Catalytic converters are federally mandated equipment. State law has nothing to do with it. True, there is no sort of test to keep you honest but if a cop pulls you over and decides to peek under your car, you will get busted.
Under federal law, the maximum fine for removing a catalytic converter from a vehicle is $2,750 per vehicle. The person who was responsible for taking the catalyst off would also be required to put an appropriate catalyst back on.
If a repair facility is caught removing the cat, the business can be fined $10,000.
Best just to get a high-flow cat and then everybody is happy.