So I was hoping I don't have to keep over-writing the xml with my own version to completely change improvements and the tech-tree, and could indeed use the mod folder.
Apparently not. What am I missing here? I found the mod directory selector in options but after restarting the game as prompted it just mashed my tech and improvements in with the original tech and improvements. Not exactly what I had in mind. Sure, I've kept certain techs that hook into hard-code with unchanged internal names (Stellar Cartography for example), but that's not the issue here.
Would a dev like to chime in and explain how to over-ride rather than add to with the mod folder? Thanks muchly.