To keep the intrigue going - I think the fact that after researching the Intruder - then fitting the best weapons you can make, that is it for the Mech.
What I suggest is adding some more research options to the mech - some options
1/ New Slot - for extras (this means the developers don't need to change graphics)
2/ New extras e.g.
a/ Fuel efficiency module - (save them turnips)
b/ Mobile repair module - (reduce HP damage by 1% per research up to 10%)
3/ New weapons - (love how the the graphic changes when the weapons are changed )
It is always a little depressing when you reach the end of a thread (Mech) now it will just become an item that you fill up and repair each battle - so lets give the mech some more legs - yeah yeah give it more legs - 8 of them , that’s a major upgrade the Spider Module oh yeah each leg could have a slot for a weapon....
OK getting a little carried away