For a long time now I've wanted to change out my (non-working) MK1 navigation system with a newer MK3 or 4 unit. The upgrade is unbelievably easy! In total I had to buy 1 part. eBay is definitely the way to go. I bought a brand new MK3 from a guy in TX for about $500 shipped. The unit, to my suprise, was completely plug and play. Simply remove the MK1 unit and video module and replace with the MK3 plugging the blue cord and navigation antenna into the unit. I was told by several forums that I would have to buy an adaptor harness, not so. All i did was update the nav software to 22 from v.17 which consists of putting in a CD and waiting.
MUCH faster processing
Different Color Schemes
Split-Screen Format (can be turned off too)
Improved Navigation Voice
BMW Startup Screen
Works With 4:3 and 16:9 Screens.
Loss of TV function (without modification)
Here are some pictures of the new unit in action.