Could you imbue higher than 57% DI?
no
also im pretty sure you cant imbue a better one from scratch.
one of the things they are working on changing is making exceptional items, and magic items better than store bought items.
right now they have it capped at 300% or something like that for store bought items. That means 3 attributes, or 4 mediocre ones.
youll want to find magic items with 100-200% total intensity with mods you like, to imbue the best items.
example
ring fcr 1/3, nothing else - great item to keep for imbuing