With a controller upgrade you really bring out the true power of your ebike. These are high quality controller that will handle the high demand of speed without burn out issues that can occur with shunt mods. These are professional grade controller with piece of mind. With these controller your ebike will double the acceleration / torque safely with the extra FETS compared to your original controller. FETS help to keep the controller cool and not burn out. Keep in mind with the stronger acceleration your battery not give the same range because of the extra power required to push ebike faster and there is a lot of wind resistance, weight, and other factors that come in play.