Horsepower Inc. | The Leader in V-Twin Fuel Injection. Horsepower Inc. (HPI) is the leading manufacturer in the v-twin industry serving over 500 dealers in the United States, Canada, Australia, New Zealand, England and Japan. It is owned and operated by Mary Jo Light. Normal business hours are 9:00 a.m. to 5:00 p.m. EST, Monday through Friday. In July of 2012, Horsepower opened a second location, their sister company Horsepower Indy in Indianapolis, Indiana owned and operated by Jimmy Light.