Zeno,

Funny thing is, more surface area requires more plate load, less needs less. It is all about lb's per square inch and friction coefficient. Also, taking material off the pressure plate cover adds plate gap thus decreases plate load on a diaphragm design of clutch spring. What you are talking about only works with coil spring lever clutches. Lastly, at 1200 hp in a diesel has the equivalence of 2400 ft lbs of torque...not like a gasser is it. The companies you mentioned are very good companies but when you speak of price like you did earlier. you may want to check out theirs, you might be surprised.

Peter