FMF Racing Powercore 4 Aluminum Slip-On Muffler w/Stainless End Cap for Kawasaki KX450F 06-08/KLX450R 08-09FMF PowerCore 4 Slip On Exhaust Kawasaki KX450F KLX450R When designing the PowerCore 4 Exhaust, FMF took a hard look at their top of the line mufflers to produce race inspired performance at a more economical price. The end result is a quality muffler that delivers improved torque, increased horsepower and rugged durability all at a price that won't break the bank. Features: Increase in power and torque through entire RPM range Durable stainless steel