See link below
Keith was fitting to a 260 but the prinicple and parts needed are the same
http://www.the75andztclub.co.uk/foru...ead.php?t=2892
Fitting isn't to bad if you allow yourslef plenty of time. One of the front seats will need to come out depending on which way you route the loom and various other trims and pieces.
No worse than fitting car radios, rear speakers and an aerial to some of the cars from the 70's where a car wasn't fitted with one.
The system can be upgraded using BMW parts to give a integrated factory fitted system that is as good as a Tom Tom.
Double din screen need a unit from an E46 you will need a widescreen TV tuner for the full display
BM24 dual tuner gives you TMC all the time and better sound quality plug and play for standard rover system
BM54 tuner gives you aux input for the BMW bluetooth funtions controllable by the screen controls but you need a bluetooth module as well and conversion leads. The sound quality is better than the BM24
BMW MK3 Sat nav computer - customise splash screen and more robust than the rover unit I can't remeber if you can get perspective view on this
MK4 Sat nav computer - you can get full post code entry, Audible speed camera alerts and Perspective view. You can add POI to this disc. (PC software needed along with a DVD Dual layer burner)
Hybrid or aftermarket digital tuner
As Jakeg says the cheaper option is a DD upgrade.