Hello, my 2005 Grand Prix L26 is from California which means I have the secondary air injection system, California O2 sensors, and California catalytic converter. Here is my question. I no longer live in California, I live in Delaware now. My car started throwing a P0420 code and so I replaced the upstream and downstream O2 sensors with the appropriate factory ones. The P0420 code persists telling me that my catalytic converter is bad. If I throw a federal cat in, will the car know the difference? I don't want the car to set a code because I didn't use a California cat. But it really sucks that California cats are almost more than double the cost of federal cats.