Cheers, will tread carefully with the aux thing.

Hypothetically then. If I end up with a 17 pin head unit but with just one antenna input, what do I do about the fact that I have two antennae out at present? Swap to a newer signal booster that just has one antenna out?

Don't suppose anybody has a link that would let me know which part number CD players are aux compatible?

Good idea. That seller has both neglected to include a photo of the label and may have even removed it because he know's it's nto Aux or MP3 compatible. Like I said, there as so many dodgy sellers out there.
Yes, and get the 5M NG antenna cable.

Search for E46 09/02 for loads of thread on it.

Cheers will have a read back through all this info and formulate a plan.

Really appreciate your help. It's been invaluable.

Quick update. Won a CD Business Head unit last night. It's a 2004 build so should be aux compatible. It's probably also 40 pin NG type but I haven't seen it yet so can't be certain. Anyway, I'm prepared for that. Have pin out's for both 17 pin and 40 pin connectors so should be able to make my cable ok. I will also need to purchase a new antenna booster if it is NG.

I figured I can test all this in the boot of the car before I start pulling seats and carpet out.

I'll likely fit a parrot and aux in as well but those can wait until I get the standard set up working.

I figure I can always sell the Business CD unit if it all goes tits up.

There is still one thing I'm curious about. We were talking about the 16:9 head unit and I realise I have most of the kit to install this. The only thing I wasn't sure about is how I turn my current single blue connector into two connectors, a blue and a white. If this sounds relatively straight forward I could still be tempted to ditch the above plan and go for the 16:9. I realise I'd have to reprogram the nav system for colour but that doesn't sound too intimidating.

You would just want to run a 5M RGB cable with the right sockets and pins on the end. The Nav end is the blue 18 pin plug (add the pins). The pins are available at farnell (£20 minimum spend), as are the 12 pin shells, and the lever housing is available at farnell and BMW. I have all and I have navcoder.

1328887 Cover 18 way
1330227 female pin
1328884 female socket 18 way
1328882 cover 12 way
1328881 404 – was female pin housing, 12 way.
1328868 male pin for MQS

Thanks Big Bob.

Might be being slow but not quite following this.

My current blue cable will still plug into back of 16:9 without modification?

I'd need to add a second cable from the back of the car to the front? This is an RGB cable like PC monitors used to use? One end would go into the white connector on the back of the 16:9 unit and the other end would go into what?

I think the pinout of the blue plug will be the same carrying power, tape audio, iBus and illum - obviously check on the wiring diargm. Than you have an RGB cable, it would go into the white connector of the 16:9 and into the unoccupied pins on the nav blue connector.

Any old RGB cable will do, as you will be cutting the connectors off. It will be 75Ohms (50R audio cable won't do) and try to get a reasonable quality cable with double screening although don't lose too much sleep over it. Get the connectors first, as they could be a PITA to find, especially the keyed white lever lousing. You may need a generic unkeyed version.

Makes perfect sense now thanks. Might work on the cable as a side project and swap over eventually. If I leave all the current kit and cabling in place it should be easy to swap over at a later date if I switch to Business CD first and save some pennies.