The STX-12F even meets the strictest existing emission standards for both the Environmental Protection Agency (EPA) and the California Air Resources Board (CARB). In fact, the STX-12F received CARBs ultra-low three-star rating in 2003

　　a full five years prior to the mandated time limit.The STX-12F features dual overhead cams, four valves per cylinder, fuel injection and an electronic engine control unit (ECU) that harmonizes the fuel system and ignition system to provide maximum performance and reliability.