The VR velocity stack was designed to reshape the factory throttle-body in order to boost air flow velocity at each given RPM. The overall shape of each VR velocity stack has undergone some of the most intensive airflow research that we have ever done to produce the best overall shape for each engine's airflow requirements. In order to achieve this we...Created a balanced airsteem between the upper and lower portion of the throttle-body blade = more airflow. We then changed the shape of the entrance to build up a higher velocity charge at each given RPM. This allows the intake charge force in the manifold to be increased = increased throttle response and added torque and power under the curve where you can use it. Streamlining the intake was also achieved by directing the air in a controlled fashion to reduce any power robbing turbulence over the AIR and PCV valve to maximize the overall efficiency of the factory throttle-body's overall diameter. Each velocity stack features a varied plenum volume whether in front of the throttle-body or in overall length to help them boost the primary and secondary pressure waves during the cylinder firing process = a tuned and more balanced induction system giving you much better overall combustion efficency = more power and better gas milage. Designed to produce power and torque throughout the RPM range, Increases throttle response, Increases gas mileage, Increases acceleration, Installs in just minutes, A patent-pending design, Eliminates the need for a ported throttle-body by smoothing and reshaping the throttle-body entrance to increase the incoming air velocity at each given RPM. In LS1 car applications, gains of up to 13 rear wheel HP have been seen (03 C5 Corvette).