FMF Racing Powercore 4 Hex Aluminum Slip-On Muffler w/Stainless End Cap for Yamaha WR450F 2020When designing the PowerCore 4 HEX, we looked at our top of the line products to deliver race inspired performance at an economical price. The end result is a quality muffler with improved torque, increased horsepower and rugged durability all at a price that won't break the bank. Overall increase in power and torque. Durable stainless steel and aluminum construction. Space Age internal packing material for maximum longevity. Internal shape of core