This isn't much of a 'mod,' but it really improves the game imo. I've given all units/agents about 50% more movement (some a bit less, some a bit more) on the campaign map. Ships have been given a lot more. You can adjust it to what you like, default value is 140 for most things and I have it 210 atm. With the bigger map I found the extra movement was really needed. Remember to backup your original file and have fun
place the file in the main SS data folder (default path is C:\Program Files\SEGA\Medieval II Total War\mods\Stainless_Steel_6\data) and you're good to go.
It is save game compatible btw.
Compatable with 6.0 and 6.1