I've got 20% on the backs and 35% on the front-sides. That's about the legal limit in GA when you factor in the mild tinting the windows naturally have. I've traveled to FL many times and I'll have to say that it was still extremely effective, and my night vision is not obscured at all.

Go with a black tint instead of mirror - you'll see the black outlines in your windows with anything not black and it doesn't look very good. Just my 2 cents.

-- Best, John