MPHD was designed to work with class 8 engines used in over the road trucks to increase fuel economy. On most applications we will see ½ - ¾ miles per gallon better simply by plugging our module up. The MPHD connects to the engines fuel delivery system and monitors the system to give these increases. You will also see a mild increase in power to get your load moving and to get over the hill in front of you easier. All applications are based on what engine you are currently running.