What Clutch you 4-speed guys (and gals) running????

FYI
A little info from:
http://www.roadraceengineering.com/323desc.htmCenterforce Dual Friction clutch.
With two different compounds on the disk, and a stiffer pressure plate with centrifugal weights, the Dual Friction clutch provides up to 90% additional clamping force.
$350
$$$ estimate
YMMV