I've been thinking about this for a while after contemplating the TNG episode "Booby Trap" where LaForge permanently boosted the Enterprise's warp core output through redesigning the matter/antimatter input into the dilithium crystals. I'd like to see a similar mission where we can gain a permanent one-time boost to our ship's performance through a doff mission, unlike the assignments that give temporary boosts to these skills.
Upon a critical success of this assignment however, the mission would be permanently unrepeatable. Theassignment would have a high failure and disaster chance and would have some pretty hefty requirements to work. The assignment could be as follows: