This 3" tensioner pulley replaces the factory 2.5" pulley and takes up the belt slack when running smaller supercharger pulleys.

Instructions are below and correspond to the pictures above. 

1. Remove the factory tensioner from the car. 
2. Pry the bolt cover off
3. Remove the OEM tensioner pulley with a T50 torx bit 
4. Inspect parts. You will need a grinder for the next steps 
5. Place the new 3" pulley on the iron tensioner and take notice of where it hits. The tensioner is not symmetrical. One side has a smaller outer ring and that is the side you need to be towards the metal. Failure to do this will necessitate extra grinding. 
6. There are 3 ridges you'll need to grind down. When there is a little black paint left in between them, you are close to completion. 
7. After grinding place the new pulley on the bracket and make sure it does not rub. Bolt down the larger tensioner pulley and re-install the bracket on the engine.