odd question about the cars with nav. I notice the NAV unit screen is completely separate from the head unit. Any idea if you can upgrade the head unit and audio equipment and leave the OEM nav in place?

or is it possible to upgrade the nav to a better Double din unit separate from from the headunit?

 

It is no problem to install an aftermarket headunit. The only issue is integrating the Nav voice, but there is an interface available: http://www.newministuff.com/new/shop...ductshow&id=51

If you want a double din Nav, just disconnect the factory Nav and do whatever you want, but you'll have to be creative with fitting it into the console or dash.