Description A stock crank pulley is designed for a stock engine. When an engine is modified, the stock crank pulley does not do it's job of keeping vibrations to a minimum. Using a special design, these pullies will eliminate much of the vibration produced by your engine. That will keep your flywheel, trigger wheel, and timing gear on the crank even at high RPM usage! The Fluidampr harmonic pulley have a precisely machined inertia ring inside along with special silicone fluid, that can absorb vibrations through all frequencies. The stock rubber dampened pulley uses rubber for dampening only for the frequency of the stock engine. These Fluidampr pullies are great for any engine setup you mave have. They do not require any frequency tuning like a stock pulley would. You will notice engine vibrations decrease, along with decreased clutch chatter if you have a lightweight flywheel. Decreased "Clutch/Gear Box Chatter" which is caused by lightweight single mass flywheels. Reduction in rpm drops when shifting in a competitive environment. Gains of 3-10whp and 5-13ft/lbs. of torque depending on your current setup. These are a must for a modified engine, especially if you are revving higher than stock. Will fit all 06A 1.8T engines! Will not fit early 058 block engines! Available on back-order! Ships in 5-8 days