Description Reviews This Supercharger Pulley Package is the best bang for your buck for the Gen 1 Cooper S! By adding a smaller supercharger pulley, you will see 15 to 20 HP (depending on your cars engine and pulley size), and you can rest assured that you're doing it safely and correctly. The 15% pulley has been proven over and over that it is the best pulley to get safe, reliable HP out of the supercharged MINI without doing any damage to your engine or supercharger. That is as long as you use the right parts with it. So we paired it up with the correct heat rang plugs and the correct belt length. We also offer in a 17% size for a bit more boost, but you will get a touch more wear on the belt. Just pick the pulley that fit your needs the best and we will take care of the rest! While you're at it, rent a belt tensioner tool as well as the pulley rental tool to make this a true DIY project. Or while you're in there add an intake to the project since you have to take the stock one out anyway! Know what your doing and do it right! No re-programing is for the ECU is needed! We do recommend doing a reset of the ECU so that it can quickly see the new change in boost and you get the most out of your new performance mod. You can find out how to rest the ECU at the end of the DT BPV instructions! 2 Reviews 5 More smiles per mile! Posted by Jim on 18th Apr 2016 Works great and installed easily! Best bang for you buck mod on a supercharged Cooper. 5 Excellent Build Quality Posted by Matthew Menze on 10th Nov 2014 Craven Speed products are shockingly well built, it appears to be produced at a higher build quality than even OEM parts. Would 100% recommend to anyone. Detroit Tuned's service is also impeccable, some of the best in the aftermarket performance industry!