Each state has its own emissions and inspection requirements. In California, this is managed by the Air Resources Board (CARB for short). CARB has determined that certain aftermarket motorcycle parts are not legal for sale or highway use in the state of California. Items subject to this determination include certain exhausts, fuel controllers, and other parts that might affect a vehicle's emissions.
British Customs has determined to the best of its ability which items are CARB approved and which items are not - items that are not CARB approved are not able to be shipped to addresses in California or used for on-road use in California.
Items that are not CARB approved may still be utilized in the state of California, provided that they are not used on a public road (i.e. only used on a closed course or offroad). At this time,British Customs cannot verify if a product is used for closed circuit or off-road use and cannot ship to addresses in California.