I have a navigation system in my Yukon, but I dont in my explorer. I was thinking of getting a portable one for it but I have never bought one before because my cars have always had a factory navi in it. Any suggestions? I was looking at a Cobra one with the red light camera detector in it and a magellean with the lifetime realtime traffic in and the bluetooth built in. Not really sure if I need the lifetime traffic or not because I can use the radio for that. Any suggestions and reccomendations are greatly appreciated!