Vertex 23383A Replica Piston Kit for 2008 15 KTM 150 SX XC 55.95mm feed mpn 819M04020 What this accomplishes is that What this accomplishes is that the ECU is told that the intake air is a little cooler than it is Product Details Tire Diameter Speed Rating Load Rating Wall Construction Tire Tube Type Rim Size Product Line Winderosa Top End Gasket Set Part Number 810869 Fitment Type Unit Sale Qty Set Style Material Color Size Finish Position Functional Length Cable Sleeve Length Cable Sleeve Travel Driver Seat Length Passenger Seat Length Driver Seat Width Passenger Seat Width Piston Cylinder Size Piston Size Added Cylinder Stroke Volume Final Engine Displacement Exhaust Configuration Muffler Size Muffler End Tip Style Windshield Height Windshield Width Handlebar Diameter California Air Resource Board Compliance FALSE Product Disclaimer which aids in the break in process and reduces wear on your new piston Items Included