I have been thinking of how to improve the defroster and came up with an idea. I was thinking of more or less trapping the hot air against the windshield until it reaches the top and have a limited space there for it to escape. I was thinking of putting a second piece of glass or acrylic on the inside overlapping the defroster vent and seal it off against the windshield gasket stopping it just short of the top side. I think it would allow you to run the heater and defroster at the same time but still keep the winshield clear. If anyone has tried this I'd like to know if it worked.