This system provides a noticeable power increase throughout the rpm range along with additional over-rev. Choose from an aluminum muffler shell with stainless steel tubing. Either features a cone-style outlet cap and inlet cone to keep the muffler as forward as possible for centralized mass. Two head pipe designs are also available, including the "Rev" head pipe that moves more power delivery to higher rpm, great for fast outdoor style tracks and pro level riders. Head pipes use the stock heat shield. Muffler completely rebuildable. Meets 102dBA requirements.Note: For closed-course competition use only.