Before unlocking all locations (especially the part of Liberty City where Alderney City is located) go to any bridge leading to a locked place to find a roadblock and police guarding the bridge. Run through or use a vehicle/helicopter to get past them to immediately earn a six star wanted level. Note: The police and police helicopters will start shooting you. To get rid of the cops, go back to an unlocked location and enable the "Remove Niko's wanted level" code. Note: If you are going to the prison but it is still locked, land your helicopter carefully in the basketball courts.