Attached to a ratchet, the socket may not go onto the bolt easily because of the fans. But if you do some twisting and turning, it will go on. I placed an aluminum pipe over it and bent the pipe. Be careful what you leverage your body against when trying to loosen this bolt. One individual dented his left fender with his hand.
Installation is in the reverse order.
I was really amazed at how heavy the stock pulley is. When you compare it to the lightweight pulley, you'll really notice the difference. I noticed an immediate gain in torque across the entire band. I have not seem any dimming of lights or other electrical devices yet. This is a list of some of the pulleys available for the Impreza.