When Harley-Davidson replaced the spring-loaded cam chain tensioners with hydraulic units in 2006 it brought a marked improvement to the performance and reliability of Twin Cam motors. Now Zipper’s Performance has taken the technology to the next level with their Red Shift Dual Piston Cam Chain Tensioners. These double-pumper tensioners are direct replacements for the stock single piston units, and provide noticeably superior cam chain stability and valve train control for both cylinders. The result is improved throttle response, increased horsepower and torque, reduced valve train noise, and extended life of valve train components. That’s a whole slew of benefits for $159.95.