The PowerCore® 4 is designed to increase the horsepower and torque throughout the entire power curve and give you a noticeable power increase that is very usable and beneficial no matter what your riding style or ability is. The mufflers are constructed from aircraft grade aluminum and stainless steel for durability under the harshest conditions. Features include space age internal packing for maximum packing life, high-flow modular end cap, and an internal core shape that uses high-flow technology. Enhanced sonic evacuation provides for higher flow and increased power. Includes removable spark arrestor.