PERRIN took their classic WRX pulley and modified the rear belt keeper to make for easier installation on the new 08+ WRX and STI. For those who have not seen these, there is no AC belt tensioner anymore and you need to stretch fit the belt onto the crank pulley. This was made even more difficult with the older design.
Weight reduction is key to making the best use of any available HP and torque. In no place on our vehicle is this more important than the rotating mass found in the engine. The PERRIN Performance Crank Pulley is 4-pounds lighter than the stock crank pulley. This reduction is equal to removing more than 100 lbs of vehicle weight! Throttle response, horsepower and torque are all increased with this easy to install product! The PERRIN crank pulley is cut from 6061T6 aluminum, anodized black and laser etched for increased belt life and a precision fit.