2 questions:
Do the larger machines only connect to the ducts? Because Maraxis locks them behind the planet, creating a rather obvious issue.
How mid-game install friendly is the mod? Will the things already placed just continue working, or suddenly break and demand some attention?

Overall, I love the concept. Always wanted a bunch of huge machines, because normal foundries look kinda wimpy. And the usage of concrete trenches for decoration in the screenshots? Great.

They only connect to ducts, no other pipes. Not sure what to do about maraxis yet, but I'm open to suggestions

This mod is NOT midgame compatible; it will make your existing machines blow up in size

I think a simple solution would be to add the needed duct parts to the techs that unlock the big machines. There's nothing that prevents the same item being unlocked via different technologies, I think, and that would solve the issue of Maraxis moving the tech behind itself.