Which preload are you speaking of? As far as I am aware, nothing should be preloaded, unless you are speaking about the clamping force induced on the clutch disc by the pressure plate as you tighten the 6 allen screws on the PP. Those should be tightened ALL the way down to 19ft-lbs IIRC. They are sort of a pain too as you have to go around tightening all 6 a couple turns at a time so the PP seats properly.