x2, my old KC used to feel stiff, i used to have clutch cable problems. the last cable i got was a maximum motorsport, and i HIGHLY reccomend their cable. it made the KC feel the same as stock like it should maybe a tad softer. i tired crappy parts store cables, and a i had a FRPP cable for a year or so and it worked pretty good. but the MM is the best hands down.
i then since upgraded to a ram powergrip HD clutch, which is stiffer than a KC and its an awesome clutch, and the pedal effort is good and fairly easy for how much holding power the clutch has.