I have 20% all around and 50% on the windshield... have had this exact setup on my past 2 cars and all my buddies have it on theirs. I never got pulled over once for it, never mentioned on the numerous stops for speeding.
I do think 20% is too dark for a windshield though... for both visibility and the risk of getting unwanted attention.
Either way it looks good and who cares, it's your car
