Do parts names stuck at "1Z" still increase design rating?

Take this into account:
-I developed parts in Season 1 to reach the final part # of "1Z" (name doesn't go further)
-Once "1Z" was reached the max performance was 80% at the time

Question: Do all future "1Z" parts stay at 80%? --OR-- If I continue to design to 100% will any "1Z" part I decide to refit be the 100%design level part even though the name is stuck as "1Z" ??

Thank You

David,

I don't know the answer to that. I shall ask.