Naturally, extend all tech levels so the end of research dosen't hit so soon.
-Modify engines so speed is based on thrust/mass. (engines per move is proportional to mass)
-Swap around shield techs, so they have a smoother improvement as techs rise
-Alternate normal shields and phased, with phased being the same(or slightly weaker) strength but one tech higher.
-Have regenerators require shield tech plus some sort of shield support tech. (definitely fix the SR 5, since it is worse in every way than an SR4)
-Improve armor so its useful.
-Either lower the cost, improve the hitpoints, reduce size, or a combination of the above, so that they are an alternative to shields (make them equal, but different, so they're better in some situations, but worse in others. Encouraging the use of BOTH armor and shields on the same ship is best)
-Add crossover techs: combination of racial techs gets new components, could apply to standard techs too (ie. WMG + APB = Antiproton wave cannon)
-Spread out resource costs so they're not ALL minerals
-Add Heavy missiles/ Mini missiles, multiple PD options.
-Add more weapons that use the more interesting damage types. (Quad to shields missile, Phased missile, Null-space ramming warhead
)
-Mines should have LOTS of warhead damage types.
-Price vs durability mounts for non-weapon components.
-Size vs price/durability for non weapons