Performance Supercharger Pulley for the Jaguar XF Supercharged We are proud to introduce an affordable supercharger pulley upgrade. Get the most out of your R's supercharger. This kit is designed to deliver an extra 17-21 HP (at the wheels) by getting your Jag supercharger to produce 2.5 Lbs of additional boost. Supercharger pulley upgrades are unlike other mods because they provide HP gains throughout the RPM range. Intake and exhaust systems are good for low and top end performance, but only this upgrade can help improve your mid range performance. For that reason this pulley will deliver performance in a way you have never felt before. Installation is very straight forward. Our specific instructions will take away all the guess work. Any reactively well equipped mechanic will be able to install this part without a problem. You don't even need to change your existing belt! If you have any questions about this part please feel free send us an e-mail with your number. We are more than happy to answer any questions you may have.