Last night I installed the UUC Big Boy 2.0 clutch stop in my 2002 530i. Here are my thoughts:
First of all, the stock plastic POS clutch stop isn't worthy of this car. It is quite embarassing and many people have found the top part of it rolling around on their floormat when the head snapped off the bolt. In addition, the plastic bolt threads were stripped badly.
Second, there are three clutch variations in the e39. Before 1997, there was no clutch ignition safety switch. Therefore the UUC clutch stop can be installed and adjusted at will.
From 1998 to 2001, there was a separate clutch ignition safety switch that could be bypassed. After installing the clutch stop, people glue some sort of spacer (felt pads, rubber grommet, wood) to the clutch arm to depress the clutch ignition safety switch before the clutch stop is reached. This takes a little work, but is an easy DIY.
For 2002, the clutch ignition safety switch is integral with the clutch piston (under the dash) so that it can no longer be bypassed. The only way to install the UUC clutch stop is to cut the bolt in half, and keep 1 of the nuts provided and the washer on the bolt. The result is about 1/2" to 5/8" shorter travel. This is what I did for my car last night.
I am satisfied with the result, although I feel like BMW has screwed us by making it impossible to bypass the clutch ignition switch (they must feel strongly about it for some reason?!?). In any case, the Big Boy is nicely built, robust, and a lot wider than the stock piece. The shorter travel is noticeable and a good (not great) improvement over stock. I would do it again, but wish I could cut travel another 1/2". I am a little pissed at UUC for not posting anything on their site or in their instructions about the different installs. Must be because of liability, but then again, they are liable whether they post instructions or not. Must be why the price is a whopping $20 for a $3 part.
Just thought I'd post my experience for the benefit of 2002 owners who might expect a troublefree installation.