For those of you who want less heat get some metalized film. I have some very light (43% tint) on the font windows of my truck which blocks 50% of the heat. It really does a great job making the cab cooler. You would have to get into a very dark regular dyed tint to get that much head blocking (if you could even get it at all).
Oh and metalized films won't turn purple because the metal in the film gives it the tint.