Modifications to continuously variable transmissions (CVT) are presented in order to improve overall performance in recreational vehicles. A computer controlled CVT would eliminate performance-inhibiting compromises currently imposed by mechanical sensors and actuators. The authors propose a computer controlled CVT to obtain improved performance. This paper considers a snowmobile modification that is a stepping-stone towards a fully computer controlled CVT. External force was applied with a pneumatic cylinder and four bar linkage to the driven pulley to vary sheave pressure and override the natural shift pattern. An external force of 431 N increased track speed 59% during hill climb testing. Ultimately, a microprocessor would use input signals from track speed, engine speed, and throttle position to shift the CVT to obtain maximum performance.