The COBB catback exhaust for the WRX & STI does not deviate from the factory emissions equipment and conforms to the SAE dictated 95-decibel exhaust noise level limit enforced by California, as well as other states in the US. This system is modeled after the stock factory exhaust fitment locations, therefore making it an easy direct bolt on item inclusive of all needed gaskets and hardware. The COBB Tuning catback exhaust is heralded often for its quality, performance, and subtlety. Engineered to be a vehicle specific unit, the catback exhaust uses the highest quality stainless steel piping and a muffler designed for direct and efficient flow of exhaust to achieve the highest performance while still retaining a stock like appearance and sound level.