There are two basic styles of pressure plates out there. One is a diaphram clutch with many fingers for the throwout bearing to push on. This type of clutch has a fairly light pedal feel even with mechanical linkage. The other type is a 3 finger, or Borg & Beck. The B&B is a bit stronger...but also has a brutally stiff pedal feel to it.
I suspect you replaced a diaphram clutch with a Borg & Beck.
Rene