Well, I wouldn't automatically edit anyone's DLC, some of us spend quite some time on physics :P but I know where you're coming from. Even worse is the power side of things, usually - there's not a diesel in the world, even a switcher which is about as near as you'll get to a model, that behaves like nearly everything available. Beware you don't break someone's custom setup when you're fiddling though.
I'll poke this thing when I have time & inclination. I wrote my own SD40 physics & scripting years ago so I don't even go near the new ones generally.