Red Shift Dual Piston Cam Chain Tensioners are a must-have for 2006 Dynas and all 2007 to present Twin Cam performance applications. These tensioners improve cam timing accuracy and valve train control at two critical key areas; the drive and driven cam chains. The dual-piston design is simple and effective and it is easy to see why it works. When the Twin Cam engine is running, the power pulses rock the tensioner shoe back and forth. In the stock single piston tensioner design the natural shoe movement causes the hydraulic piston to momentarily unseat at the base, which interrupts the pressurized oil stream and introduces air into the hydraulic tensioner. Air will diminish or eliminate the pressure that the tensioner shoe places on the cam drive chains, allowing loss of valve train control leading to "bouncing" components including valves, spring collars, rocker arms, pushrods, lifters and camshafts. The Dual Piston Cam Chain Tensioners restore critical camshaft timing events for both cylinders, improves throttle response, acceleration and smoothness and increases horsepower and torque throughout the entire RPM range.