I've got an 05 Carrera S and would like to consider adding navigation to it. Anyone have an idea what that would cost at a dealership? Is there an aftermarket version that is better or less expensive that still functions over the disply screen and uses the same buttons/commands? I realize I have an option of doing a separate unit on the windshield like a Garmin Nuvi, but first want to consider a factory compatible addition.

 

In the 07s the screen is ready for the module and program. It's about a 3k upgrade. If you've got the screen in the 05, I'd expect it to be the same.