Well, turns out the SL is a 160, with 145 effective edge, 18.5 waist and assym core, sidecut and camber.
It arrived a couple of days ago and I rode it today between lessons and found it producing a slightly wider track on the heelside. Then I accessed a dark corner of my memory I remembered that it needs a diagonal movement rather than lateral, pictured Nerva and Bauer waving their arms around...and had a blast!
Assyms are a the "Dogs Bollocks"! You do need to have your act together, this is one powerful puppy. I think I will actually race on it.
Thanks for the info guys.
Martin