Measurements of the Akrapovic EVOLUTION system on the KAWASAKI KX 450 F (with muffler insert): Power & Torque: The Akrapovic Evolution and Racing systems deliver a performance increase throughout nearly the entire rpm range. It is most pronounced in the bottom and the top of the range. The systems deliver increased torque similar to the power increase. Max. increased power of 2.5 HP was measured at 9900 rpm, while max. power of 48.5 HP was measured at 9000 rpm.