Not to take this thread too far off course, but if you're having 'side-to-side' slop issues, check out UUC's delrin clutch pedal bushings. At $20 they are woefully overpriced (ahem, mentioned above regarding pre-fab clutch stop too) and don't forget shipping is extra, but it is worth it. They replace the plastic split rings on either side of the clutch lever swing point with solid pieces of delrin. Your pedal will go straight to the floor and straight back and never feel sideways again. They also include a couple of washers to use as 'spacers' in case your clutch pedal has induced a severe amount of sideways slop over time.
For my M3 I accompanied these with an aftermarket all metal clutch pedal and now I've got sweet sweet short and linear actuation instead of BMW's definition of clutch movement. They claim this pedal works for the Z3's as well (or at least that they have a version of it for the Z3).
http://www.masonengineering.net/Subp...W_Products.htm (scroll to the bottom)
http://www.masonengineering.net/images/Clutchpedal2.jpg
PS> no clutch stop necessary with this thing, its sweet.