I was told HID although it uses less power (35W) actually generates more heat than conventional halogen. Oh well, we shall see in due time
On the subject of using soap water, I think I may just give it a try on the other side. I've only tried sticking 1 side on
Think soap water should be transparent and not remain visible after it dries. Come to think of it, that's how the guys here apply heat shielding to my windscreen of my previous car. Plenty of soap water on the inside of the windscreen and some squegee and heat with a hair dryer
The Stoneguard instructions actually says if there's air bubbles present, the Stoneguard can be peeled off and reapplied. Let's hope it's true...