I was trying to get this to work yesterday as well, I ended up removing HETTN and manually cleaning out nodes I wasn't using in the ETT cfg. Then I realized I would want an update of the mod and was likely to add more mods that would use parts I had culled out... I edited the 'Eng Tech Tree.cfg' in Notepad++ and just did a replace all of 'hideempty = false' with 'hideempty = true' and that accomplished what I want, getting rid of about 40 empty nodes. I think the issue with HETTN might be d