When you have a wanted level of any number of stars drive your car inside the pay and spray but before the door closes get out of the car. Aim your gun to look ahead and the cops, FBI, even the army will walk right by you even if you attack them while inside the pay and spray they wont see you. To get more cops to enter the area just exit the pay and spray and enter again. When you have grown tired of fighting just enter your car and the pay and spray door will close and then drive away with a clean slate.