The Dayco Underdrive and overdrive balancers are a great way to increase the performance of your factory supercharged car. These balancers feature pulleys that are either larger or smaller than the factory supercharger pulley. Spinning the supercharger faster will increase the amount of supercharger boost pressure and in turn, increase the horsepower of the engine. Installing these pulleys does require professional dynamometer calibration of the engine computer by a qualified shop. And additional parts such as larger fuel injectors may be needed to take full advantage of the increased boost. Dayco offers professional advice and assistance in choosing the right balancer for your engine build by calling our tech line or using the contact us form on our website.