I just sat in my first 300C today... very very nice (this coming from a long time Ford guy). It'd be tragic to remove the Nav system, so I think the ashtray/cig lighter area would be a good route. You still have plenty of storage for the driver. It's such a new car that you'll probably be the first to do it.

FireFox31, you should see the '05 Mustang GTs we have zooming around here.