This Air Density Meter is a great tool for serious engine tuners. It could help you determine if the jetting or fuel mapping should be adjusted. Altitude, temperature and atmospheric pressure can affect quickly the performance of the engine. This Koso meter will instantly tell you if the condition has changed so the proper changes can be made on the engine. This is a must for performance enthusiasts since it will help get the extra horsepower out of the engine or it could even save the engine from bad damages.