Got to agree with mowermech - try explaining the interstate commerce laws to a state trooper on the side of the road and you're hosed. Virginia can't make you get an inspection sticker to drive through the state, but they sure as heck can nail you for having a radar detector in use. Besides which, I don't believe there are that many states that don't require supplemental braking anyway. It's just not that hard to do. We use the Invisibrake in our Wrangler - permanently installed, never any equipment to mess with, doesn't run down the battery, completely out of sight and works great. I might not worry about my own safety sometimes, but I'd hate to think I hurt someone else by trying to save a few bucks and a little hassle.