Tricky buisness indeed Kirin! You might want to get the heater to someone who really knows them to give it a real going over, they are sooo tempramental. When I installed mine, I made a template of the holes that needed to be made on a sheet of cardboard by lineing it up to the heater, then too the dimensions off that and applied them to the car. It worked like a charm! Airspeed has a set of instructions you can borrow, hard as hell to read, but it'll give you a starting point. Lost of info online on how to deal with these beasts.