Unfortunately due to issues with random discrepancies with drag when mirroring (thanks @Gestour and @EternalDarkness for help with that) i now know why my vehicles have a tendency to randomly yaw to the left or right. I have found a long and dull way to fix it using notepad ++ and a lot of searching through the xml files for mirrored parts and their drag and then slowly editing them but I read on a post made about the in game xml mod Overload that one could edit the drag scale, but i encountered an issue with it.

How do you add a configurable label to the parts list. Usually you can click a little plus at the bottom of the list of variables and add a new one but this doesn't seem to be the case. Is this because my version of overload is out of date or is there a different method.

Either way thanks to all of you who answered my past two questions as it really helped both a car and a boat I was working on.