Get the platinum tint! I think you can get 10% in back; bro went to a shady shop in San Mateo, but they only agreed to do 5% tint on the driver and passenger windows. If you're gonna do it yourself and want some cheap tint, go to home depot's window section. You can get the tint for mad cheap! Hope this helps.
I have some pictures of my bro's car with platinum tint, but it's not a BMW. I will post the link if I don't get flamed.
