From: Australia, mate
Engine problems aside preventing you from doing much more with reactors, you can still definitely at least balance the other aspects of this mod.
The Zenox racial shield has the exact same stats as the stock "fast" shield at the final upgrade for both, the only advantage the Zenox one has over the regular fast one is that you can get to the end slightly quicker. You could possibly make it one or two points smaller in size, rather than just outright buffing its speed and endurance.
And also, maybe it's just my own preference for ship-building, but the balanced shield seems to be simply a superior choice to any of the other paths. It's not that much slower than the fast one and it's not really that much flimsier than the tough one. I don't think this should be fixed with a nerf though, rather a minor buff for the other three shields instead. You should also position it in the middle of the two other non-race specific lines on the tech-tree, because it just seems sensible that the balanced shield would be inbetween the two extremes.
The final colony module only has two required techs, when the second colony module has three.
Add just one or two more tiers to each of the three engine types.
It's also good to see that the one that "turns on quicker" is still completely useless, and now that the advanced FTL is gone completely, I don't have to waste time researching it as a stepping-stone. Although, at least the efficient one is a choice I'd genuinely consider now. ;)
Some of the construction techs are slightly redundant in terms of ship size gains (I.E, there are no ship-size gains).
My personal preference for fixing around this doesn't really fall in the realm of game-balance; but it'd be nice to see the overall ship-size in the game increase, with an exponential rise in size for each of the later-end techs. Possibly to a maximum of 1750 or even as far as 2000.
Alexander the Great, his name struck fear into hearts of men.