Is it gonna block the ability to look in completely? Basically the thing they look at is if they pull you over can they see inside the vehicle for passengers. If you are only blocking back window or partially obstructing the rol downs they should leave you alone unless you give them a reason to be a a hole. You roll in and ask they will try to find something wrong its usually safer to do it not bring undo attention by keeping vol down in residential areas not driving like an idiot or smoking weed or anything. As long as it does not alter the normal operation of vehicle you are not violating laws. Now if you are blasting all out at 2 am theres a little bit of issue
