I am a recreational pilot and have a RV-9 in an unheated hangar about 60 miles from my home. In 30 years of light plane ownership and experience with the full spectrum of engine warming techniques; bare light bulb, propane forced air, bolt-on heaters, floor mounted ceramic heaters, etc., I find the The AeroTherm Alien and RCS setup the best warmer available. I especially like the ability to control the unit remotely and use it only when I want to fly. There is no requirement for modifying anything under the cowl or having someone from the airport plug the unit in when I need it heated, or unplug it if I cancel.