Important Note: This piston is for a stock sized bore. Please measure your cylinder to check clearance before ordering. By using a Pro Circuit high-compression piston you will gain both low-end torque and top-end power. High-compression pistons work equally well on stock or modified motors with the same results, more power at every RPM. Pro Circuit developed their High Compression Piston with the intentions of satisfying the need of your motorcycle's thirst for more power. An exclusive motorcycle engine upgrade that has the ability to boost low-end torque without neglecting top-end power. Increases overall power whether you are running with a stock or modified head making this an easy way to step up your bike to a whole new level. The power gain does not have to come with the price of expensive race fuel; the piston works with premium pump gas.