 In addition to the high performance business, Roush supplies propane conversions kit for the F-150, as well as for school buses.Roush is listed as a vehicle "Manufacturer of Record," in that the company modifies Ford F-150, Ford Focus and Ford Mustangs to the extent that they are considered "Roush" vehicles, and some carry Roush factory warranties (as opposed to Ford warranties).Modifications to Ford vehicles completed at their Livonia, Michigan factory include upgrades such as suspension, body, interior and engine, depending on the model of Roush vehicle and the options ordered.