I may be wrong, but the way I understood the "cat" regs. It is/was not legal to remove/bypass/etc the cat from any vehicle that had one installed from the factory. The 50,000 mile 5year requirement made it necessary for the OEM to replace any failed emission equipment during that period, regardless of the OEM vehicle warrenty period. There is a stiff fine related to disabling any emision equipment, but does anyone know of it ever being applied to an individual vehicle owner? I would not worry about it, unless you are in a juristiction, that has MV inspection. I would, however, keep all of the parts, in case you wish to sell the vehicle into an inspection juristiction, or if regs are put in place for inspection in your area.