Upgraded again:

Now i succesfully replace the center cargo bay into 6 overlapped big cargo blocks occupying the same space and expanding cargo space x2, also replace both internal motors to overlapped versions too, now has a bit more velocity, energy and maneuverability.

+Cargo space (2k)
+30% More energy
+25% pitch maneuverability

Upgraded:
Now i replaced normal generators, energy containers and trusters to overlapped versions to maximize the limited space

+Energy
+Stored Energy
Almost +50% more maneuverability