To be able to determine if your car is a California or Non California Emissions car there should be a sticker on the door jam, the drivers door or under the hood that will specify if your car was imported with the California Emissions. For the Non California design the converter is 14" long instead of 15 7/8" and the down pipe is also 1 17/8" longer as well. If you are replacing the converter or off road you will need to know which one you need but if you are ordering a complete system the shorter down pipe will make up the difference of the longer converter or off road. If you are ordering just the converter or off road along with the cat back system then you will need to order the converter or off road pipe that is designed for your car. If you are odering a down pipe only we will also need to know if your car is a California or Non Caifofnia design.