Supposedly LUK makes most clutchs, including the centerforce which centerforce then add the weights and such to call it their own. I too run the standard F-250 LUK clutch bought from Napa, it is stiffer than a stock mechanical system which came stock on a bronco, however it doesn't make my leg sore and I wouldnt call it super stiff or hard to push. Standard metal/cast master from Napa as well. My clutch releases toward the very top of the clutch movement. I just welded a metal tab on the back side of the clutch pedal to hookup the master rod.