technically its illegal to have tint on the windshield in all 50 states. honestly if youre uncomfortable with the idea of being pulled over due to having too dark tint, you should probably go with whatever your states legal limit is. a few of my buddies have limo tint (5% transmittance) on their cars and have not been cited for anything yet. if you live in a podunk little town or somewhere with really low crime, you MIGHT run the risk of being pulled over for having dark tint. i'd say if anything, they'd target you for speeding and possibly, if they're asshole cops, slap on an infraction for illegal tint. chances are, if youre pimpin the 3, youll be driving with your windows down, so the hotties will have no trouble seeing you, and concordantly laughing.

sorry, but it had to be said. most tint people will charge you $125-$150 from my experience.
personally, i have 20% all around on my 6, its uniform, and pretty subtle. you can see shapes inside the car, but you cant distinguish many details. pics are on my cardomain site on page 2 if you wanna see some examples.