Jetprime - Precision Control, Supreme Quality Jetprime Velocity Stacks for Yamaha YZF-R3 These velocity stacks mount inside the air box and have been developed to improve the air intake during the phases of opening the throttle. Due to the particular shape, this allows a reduction in air turbulence during the suction phase, improves the air intake from inside the air box, facilitates the intake and reduces the response time of the engine especially when you have a sudden opening of the throttle. The shape and length of the velocity stack has been designed to work at different engine speeds, to increase the suction strength and to improve the coverage at low engine speeds. Manufactured using aircraft quality 7075 T6 aluminium using some of the most modern CNC machinery available. Part No. JPRATR006 Model compatibility Yamaha YZF-R3 2015 - 2018