20% is the lowest you can go legally in the front. IN FLORIDA. It really isn't all that dark. However, I think overtinting is just a stupid ticket to get, so I say stick with the 20%. Do it all the way around for an even look. The back 3 windows will already look slightly darker because the rear windshield is tinted and the front is not. So dropping their tint to 15, 10, etc. will make them especially dark. I'm not sure how using 25 or 30% tint on the back windows would look.