I am going to attemto to do mine on my 335D this weekend so will post on here how it goes. The only thing I am slightly nervous is getting the EGR exchanger off with the various bolts.
I plan on siphoning as much coolant out of the expansion tank before I start to undo anything to minimise spillage. I also plan to leave the under tray in place and if any coolant does leak it will drain out?
Another thing I am slightly wary about is bleeding the system, do I add coolant neat and then water on top or do I mix coolant and water (50:50) in a container and then pour?