Just kidding,
I was speaking to the No. Am. disributor in Vegas and the MZ are being discontinued over a period of time. Prokart will still run them for now. The compund is the same in both tires but the contact patch is more squared off on the Mz and rounder on the FZ. The only diffence seems to be driver preference.
Their web site is.
https://www.mgtires.com/2006/index1.html
Rick