clutch shouldn't slip at all when installed. did you rough up the flywheel. when a clutch fail's or slips too much it's because it got hot(or old and worn) if it gets hot then the metal on the flywheel gets a nice sleekness to it that makes it smooth, it should be a lil rough(750grit sandpaper works). flywheel is also supposed to get resurfaced or replaced so that the clutch and wheel match up perfect without dips or anything. hell when i got my stealth's clutch done i stalled it because it griped so well