The RS-4 muffler was developed in conjunction with the Yoshimura Suzuki Race Team with one purpose in mind: winning championships! That goal was accomplished during the 2010 AMA Supercross and Motocross season, as Ryan Dungey and his Yoshimura powered RM-Z450 shook the motocross world as the first rookie in the history of the sport to dominate both series. The new RS-4D builds on the technology that has made the RS-4 a force to be reckoned with on the racetrack, enhancing it's rock solid performance. By increasing the amount of open area at the exhaust outlet, the RS-4D increases airflow, resulting in smoother power delivery and increased throttle control. Preliminary testing has shown that it offers increased horsepower and torque throughout the power curve, especially in the bottom to mid RPM range.

• Ultra lightweight carbon fiber end-cap cover
• Unique dual outlet design
• Increased torque and horsepower throughout the power curve, with most gains in the bottom to mid RPM range
• Smooth power delivery allowing easier throttle control and less clutching
• Dual tip allows for more flow by increasing outlet open area when compared to single outlet designs
• Dual inserts for horsepower tuning and decible reduction