The Tungsten stylus is a tad larger in diameter that the stock stylus, but still a good fit for the Z silo. The groove is even in the right place to work with the Z's catch.
I'm a little concerned that the groove may damage the catch over the long term, though: because of the larger diameter, it puts a little more pressure on the catch, making it harder to disengage. Since the catch is plastic, and the pressure it exerts comes from bending that plastic, I think it might shorten the life.
But it's possible that I'm being too cautious because I'm not an expert on plastics.
What I did to allay my concern was pop the Tunsten stylus in a lathe, and cut the wall of the groove so it slopes more gently toward the tip end. Now it slides out more easily, and doesn't feel like it might be putting strain on the catch.
Ran