Well, its not so much of a "mod"
.
I just wanted to change the ship sizes to make them larger.
So I made a complete copy of the subdirectory, then edited the shipsizes.txt and made the ships bigger.
When I changed one, the game loaded ok.
When I changed them all, I get a "your a big fat dummy" message that the game can't load that file.
I thought it was ok to mess with this stuff, was I mistaken?