I have a non-navi myself, and actually prefer it here in Karachi. No chance of 'chori'.
Installing it later is not easy. There's basically 4 components which go hand in hand for this to work. The additional info display panel at the top, the navi itself, the music head unit at the bottom and the unit which is installed under the rear speakers panel in the trunk. Then there's the startup disk, etc. Not to mention that its pretty much impossible to remove the non-navi unit without leaving some marks on the other dashboard panels.
