The bars arrived and they don't fit the BMW engine bars inspite of what the Wunderlich catalogue says. Well in their defence they do say that in some cases they may need slight tweaking but in my case that would require major bending!
I guess that the Hepco engine bars and presumably the Wunderlich ones must be staggered either side so that they remain the same distance in front of the cylinders. The BMW bars are straight across so one side of the tank bars is approx 1" out.