PROCOM Performance CDI for the Yamaha YZ450F (2003-06) increases the rev limit by 750 RPM over the stock rev limit. In addition, this unit offers a re-mapped timing curve which yields a noticeable increase to horsepower and torque over the stock CDI. This CDI box is a direct plug in replacement CDI. Simply locate and remove the stock CDI, and plug the Procom unit directly into the wiring harness, no modification needed. Suitable for stock and modified machines. We cover all our PROCOM Performance CDIs with a full one year warranty.