I installed one of these heaters in my p500 this summer after seeing solrus's post last winter. I installed it under the hood (I don't run thru water or mud holes) and replaced the cup holders with rotating vents. The vents turn so I can point them at me and the passenger or at the windshield to keep it from freezing up. I use my machine for ice fishing almost every day and plowing in the winter. I also added a remote so that I can turn it on 10 min or so before I go out and it is very warm inside (75 or so) when I get in it. The heater runs off of a secondary isolated battery that I installed so that it will not effect the starting when it is -10 outside when I come in from fishing. The heaters have really come down in price and you can buy one for under $150 and they give you most everything you need in the kit to install it.