I have a factory Ford Clutch from SHONUT that has about 15-20k miles on it and already its starting to slip if I shift too hard and sometimes when I try to downshift to 3rd from 5th at speeds over 45mph. How much life do you think I have left in this thing before it gets to the point of being not driveable?? The trans shifts fine, not incredibly smooth but not bad at all and the TOB isnt making any noise. Any ideas how long Ive got before I really have to replace it?