Please note that we've updated the Mount & Blade II: Bannerlord save file system which requires you to take certain steps in order for your save files to be compatible with e1.7.1 and any later updates. You can find the instructions here.
I'm new here so i hope this is the right sub to post this in.
I found out that there are hidden item components for horse armors like "speed_bonus" charge_bonus" and "maneuver_bonus" which can be edited in /ModuleData/spitems/horses_and_others.xml.
Editing these components works...