You might as well go for the 3G+ head unit as the prices are not that much more than the 3G high. My car came with just a concert radio with B&O and I did the retrofit of the 3G+, DAB etc. It is not as difficult as people make out. I even made my own wiring loom and with a good quality set of trim tools and torx screw bits you are away. The good thing about the MMI system is most of the communication is by the optical MOST cables arranged in a ring. The MMI head unit communicates with the DAB radio and B&O amp using the optical wires and the DAB radio communicates to the B&O amp using the same system. Prices are cheaper now than when I bought mine but the main bits now are roughly £350 for the main unit, £100-150 control panel, £100-150 screen, £200-300 DAB radio, £250-300 MMI B&O amp, £50-70 MMI gateway. Best buy from big car dismantlers to avoid nicked parts. Lastly, component protection can be removed by a number of independent VAG specialists.