Increases overall RPM limit. Advanced timing curve. Easy direct plug in replacement to stock CDI box. 6 Month Limited Warranty. Expertly crafted from premium materials. Quality design and workmanship. Durable construction for long service. Rev Box by Big Gun®. If you are looking to swap out your stock CDI box, the Big Gun Over Rev Box is an affordable alternative to highly-priced Orig. Equipment replacement boxes. It increases the overall RPM limit over the stock box and advances the timing curve.