05 HONDA CRF150F: Big Gun Rev Box Big Gun Rev Boxes are designed to increase your RPM limit by approximately 1,000 RPM depending on the model of your machine. In addition, Big Gun&#39;s Rev Boxes are remapped with a built-in timing curve which provides noticeable horse power and torque gains. Big Gun Rev Boxes are an easy plug-n-play installation.Increase your RPM limit by approximately 1,000 RPM while advancing the timing for a bit more torque on the bottom end.Enhances the power curve and adds up to 3 horsepower.Includes everything you need Note: Image is for display purposes ONLY; actual product will vary with fitment.