I've only had my car a few days, but I have to say I am a bit underwhelmed by the shift knob. Doesn't have the feel I like, and certainly is nothing to write home about in the looks dept. Seems many are reluctant to make the change because you have to essentially trash the knob to get it off... Yes you do, but it's worth it in the end. I have a good selection of knobs I like to rotate around in my cars. Seems I had an old Team Voodoo Pearlescent Magnum in the toolbox from an old Miata I had. Guess what? Threads on perfectly and the pearl matches the trim perfectly. The shaft on the Z is 10 x 1.25....Same as the Miata which expands the potential offerings out there.. I found a large grommet to take up the space between the knob and the boot top (though a Zip tie underneath will work as well..). Turned out great. More direct feel and a shorter throw as the Miata knob is lower. You can get the Team Voodoo knobs in various finishes here:
Team Voodoo shift knobs
Several other Knobs pictured on the Z at my "Knob" album here:
Shift knobs! album | Ttschwing | Fotki.com