u mean the top area about 6" wide on ur front glass rite? Lots of my friend did it. some with transparent sticker (overlayed on the existing sticker) and some with pure flat black sticker. Never heard wheather they have ever been summonses for that. I think oklah.
But the problem is, if u use non-transparent sticker, how much visiblity can u have on ur front screen then? Especialy when u driving down hill and infront of u is another hill to climb? or driving on highway with 90 degree hills at both side of the road (Land slide area)?