The local Ford service advisor told me that if you put a double din system with bluetooth, gps, etc it will draw so much power that the stock alternator/battery won't handle it. Seems it causes the lights and inside and out to dim when at idle...Don't know if that is true or not but if anyone out there knows for sure I'd like some info.
like Deadeye said, I have a real hard time believing this . . . I do not believe that these cars have THAT crappy an alternator and/or battery that they cannot handle a half decent head unit; what about the cars that came with NAV, do they have a completely different / upgraded alternator and battery? doubt it
If you were talking about a huge system with power amps and a trunk full of subs that would be a different story