Factory racing expansion chamber 250-300 (EXC, SX, XC) 23-25Suitable for standard silencers Untreated surface Uncompromising race look Sensitive response Increased performance Improved throttle response and increases in both power and torque Substantial weight saving Saving almost 20% weight compared to the stock expansion chamber (ca. 0,4 kg) Approvals: CCCUO_EU, FIM Factory Racing: USED BY FACTORY RACING Surface: Natural untreated