just curious and checking to see what files people usually mod and/or mod the most. this could be files you have downloaded to use or your own modified files. i keep mine fairly basic so there is less to replace if i ever have to verify my game. i do know there are some out there though that really get into modifying their files to the point it is almost a different game (figuratively speaking).
the basics of mine,
film grain removed
winch line changed
winch points changed
border removed
fuel cistern and tanker recolored
fire proof exhaust recolored
tattoo shifter
key/controller overlays removed (although yet to figure out how to get rid of the overlay box for it)
mudrunner mod (STplus as most call it)
steam icons removed
and i know there is a few others, but can not remember what or they are little things that are not that important.