I figured you(Davey)would probably go with one of Seb's Boost Lockup jobs:
http://nlrsystems.com/boost-controllers/nlr-boost-lockup
Oh, the price gone up, it wasn`t so long ago i bought mine and paid something like 850 or 890. Sold it for 600 nearly unused, the guy got it cheap
Why did you sell yours? Multistage instead?
It`s a land speed bike, no need for dragbike style clutches.
Just a basic two stage, i think it`s a RPM. We could not keep the grip on the boost clutch after 500hp. First aid was to replace the inner smaller friction plate with the same size as others, but it took us just a little further. Maybe if the basic springs changed to even stiffer could help, but don`t want to risk it slipping at any point. Now, with the basic lockup and lots of weighs in the arms its still holding on with 370lbft of torque.