from some research I did, Clutchmasters holds more power with less clamp force than SPEC...........just based on that it shows how much more advanced CM is. If my decision were between those two I would go with Clutchmasters hands down.
Keep in mind I don't have experience with either of these clutches on my car so this is soley based on the information above.
Here is an example. Spec Stage 4 rated to hold 339 ft-lbs of torque (all clutch companies measure this rating at the flywheel, just FYI)............and it takes 2000lbs of clamp force to accomplish that.
Now the CM4 on Tom's car has held 440hp at the wheels, which is over 500hp at the flywheel, for a long time and many, many trips to the track on slicks. They accomplish this with only 1500lbs of clamp force.
And to put it into perspective, stock clamp load is roughly 1050lbs.