I recently purchased a new 2021 ZM with the intent to do massive upgrades. I have found there is actually not much at all that needs upgrading. The first thing to note is the standard PRS SE nor the USA Core Pickup rings fit the Zach Myers, and I need to find cream rings that will fit. Any help here would be ... VERY HELPFUL! Full Mod Report: I have been taking a close look at the nut and comparing it to a Core USA nut and they look identical but I am not ready to say a USA nut is used, but to my eye, it looks different than SE nuts I have seen in the past. I have confirmed the nut on this is made out of the same material as the core nut and they are no longer using the cheap plastic nut. THANK YOU FOR LISTENING TO US! The nut DOES NOT need to be upgraded. I upgraded the tuners from the stock tuners to phase 3 locking vintage tuners. ( I actually ordered non-locking but I won’t complain about the free “upgrade” ) and the phase 3 tuners dropped straight in without having to change the bushings and the markings on the tuners are identical. ( see photos ). So I honestly can't say that these NEED to be upgraded either unless you want locking versions. The Truss Rod cover is a USA-sized cover. So if you want to replace it purchase one that is USA dimension. The last upgrade will be a full electronics swap of pots and 5909 pickups. I will report back on that once I am done.