I have an unused blaupunkt amp harness for sale... bought it for a 2004 E60 but "apparently" it will fit any bmw stereo from 2000 onwards..

the harness connects to the back of your stereo runs all the way down the side of the car into the boot (hence 5m) and connects to plug and play blaupunkt amp - transfers all speaker wires and power (although best to get power direct from battery) into amp and back down to head unit (allows a better amp to sit in between headunit and speakers)

although is designed for blaupunkt amp plug and play you can simply pull off the connectors and use with any amp no problems..

this is the product:

http://www.bluespot.co.uk/car-audio....amplifier-loom

like I say its un-used so good condition.. bought it for a project that I am not going to do now!

cost £80 brand new... if someone was to offer me £50 they can have it!

 

Im interested if still available.