HI TerminatorX5, I appreciate your reply and they were my general thoughts but it's always good to get a second opinion - I'll report back.

I will also add a signature for future reference, have spent a lot of time trawling the nav threads which are very useful.

My car is a UK model Alpina B10 V8 4.6 so the electrics should be basically the same as a bog standard E39 although it has the 'dreaded' DSP and I've also installed an intravee with a lumidock.