FMF Racing PowerCore 4 HEX Slip-On 044441When designing the PowerCore 4 HEX, FMF looked at their 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