I used to race the shit out of my Z24... do 4,000rpm dumps and all... and not once did my clutch ever slip... it made a wierd grinding noise for the first couple of feet but that was it... As it turned out, the clutch was 100% gone, and i was actully running metal on metal, and you could see burn marks on the flywheel from where it got so hot, it actully welded itself together in between gears.