Removing and replacing the catalytic converter on your car is a legally tricky issue, especially if you live in California or another state with fairly strict laws relating to catalytic converters, car exhaust and emissions. In 1986, the Enviromental Protection Agency issued national guidelines that regulated the legal processes relating to removing, replacing and installing catalytic converters. Removing a catalytic converter legally means following specific processes that you should not attempt on your own.
Due to the laws involved and the possibility for fines, you do not want to attempt this task without your mechanic. Your mechanic should document the entire process, including noting the original converter’s flaws and need for replacement.
Take your vehicle to a reputable mechanic shop that specializes in mufflers and exhaust.