Matt,
Our test puts the clampload of the stock 13" NV5600 6 speed at 3000-3100lbs. Torque capacity is dependent on clampload (Lbf) X coefficient of friction (mu) X the mean radius of the friction material (in ft) X the number of friction surfaces (one disc = two surfaces, two discs = four surfaces). Now add the variables of temperature, flywheel surface condition, installation details, (yes there are a lot of ways to screw up a clutch installation) slip time, driving skills, engine torque vs. clutch torque capacity and this should give you some small insight to the task of being a clutch system.