Reviving this thread!
I am getting ready to do the VANOS on my Z4M with the Beisan goodies as preventative maintenance along with the VAC exhaust hub. I have rebuilt a few VANOS systems on other engines, and the S54 doesn't seem like a much larger challenge except for the VANOS timing issue due to the clearance on the E85/86 chassis and the need for this switch.
Unfortunately for me, I am COMPLETELY useless when it comes to electrical stuff, and have no confidence that I would be able to build this box. I also don't like being bent over a barrel financially for special tools unnecessarily
Anyone here that built one willing to sell theirs?