I always wondered why not upgrade the visual too for the interior of your ship? I mean different bridges can be selected so why cant we have a custom engineering? I would like when you hit VA1 and get the quantum slipstream drive for it to physically change the appearance of the warp core like it did in voyager:
A lot of people have suggested this, myself included. I think each tier of ship should be able up get a new warp core installed.
The basic warp core type we get with starter ships should be what we have now. For each tier up, we should be able to craft a new core from memory alpha that gives a slight bonus to power output depending on the ship type with a secondary bonus too and a slight bonus to power transfer rate.
So for each tier up, the bonuses could be:
Cruiser: +1 to all power levels
Escort: +2 to weapon and engine power
Science ship: +2 to Aux and shield power
All: +20% power transfer rate