Don't want to be a wet blanket, AND I'm not a big fan of catalytic converters, but everyone understands that removing or modifying vehicle emission systems is a Federal offense, right? Shops that are caught doing it are subject to a fine of about $125,000 for a first offense. Vehicle owners are subject to similar fines.
There is a reference to this, but I can't put my finger on it now. Owner of a large muffler shop told me about the fines. He said undercover customers have tried to get him to eliminate their 'cats', but he always refuses.
Here's one article.
Exhaust System Repair Guidelines.
The EPA has prepared this fact sheet to answer some of the most commonly asked questions about the types of exhaust work a repair shop can legally perform. If you need any further information about the EPA's tampering policy, please call (202) 564-9240.
Under what conditions or circumstances can a catalytic converter be removed from a vehicle and a converter replacement pipe be installed?
Under Federal Law, catalytic converters may not be removed and replaced with converter replacement pipes by any person. The 1990 Clean Air Act Amendments even prohibit private individuals from installing converter replacement pipes on their own vehicles. Anyone who installs such pipes would violate section 203(a)(3)(A) and (B) of the Clean Air Act (Act).
In addition to federal law, forty-five out of the fifty States also have statutes or regulations which prohibit tampering with the pollution control equipment on motor vehicles or driving or selling such vehicles. Thus, vehicle owners who tamper with their own vehicles may be subject to substantial penalties under both Federal and State law.
The only circumstances in which a person would be allowed to remove a converter is if the vehicle is being shipped overseas to an area where unleaded gasoline is not generally available. (Vehicles traveling to Canada or Mexico are not eligible for this exemption.) In this instance the vehicle owner must have a letter from the EPA specifically authorizing the converter removal from the vehicle in question.