[Jeff Lee]

There are several dual disk units from just about any seller that would probably be appropriate for this application. Any would depend on the level of work the guy wants to put into it (is this track only?). A dual disk diaghram unit would be the easiest to set up (just bolt it in) and if he's not into setting records for lap times and just wants to go have fun, it should be fine IMO. But if he has sticky track tires and is putting a big load on everything, it could break parts and or loose traction (could cause a wreck) just like a drag car. You can adjust the slippage on a diaghram clutch by increasing the installed height. I would suggest a data logger is a necessity if he's looking for that level of tuning.