Big Gun Exhaust 40-R03 Rev BoxBig Gun Exhaust 40 R03 Rev Box If you are looking to swap out your stock Honda CRF 150F CDI box, the Big Gun Over Rev Box is an affordable alternative to highly priced OEM replacement boxes. It increases the overall RPM limit over the stock box and advances the timing curve. Increases overall rev limit to 10,000 RPM Advanced timing curve Easy direct plug in replacement to stock CDI box 6 Month Limited Warranty Big Gun Exhaust 40 R03 Fitment: Honda CRF