Installing a pulley on an Subaru with an EJ engine such as the Impreza or Legacy is pretty straight forward. Basically just lock the engine either by putting the car in gear or using something such as my pulley removal tool to lock the engine as you loosen the crank pulley. Once the bolt is loose, work the pulley off and replace with your new lightweight pulley.
Stock Impreza RS Pulley Removed
Stock RS Pulley compared to the Lightweight Pulley
Belts Removed
Pulley Installed