I have modded the GC2Types.xml to add a new hull design that can hold more than normal medium hulls, and also reduced the ParticleBeam size to get the feeling of modding dynamics. Yet, the AI was faster than I and used this newly added hull to destroy my bases. Here is a screenshot of the ship that AI come up with:

Now, that is good for the GalCiv2, but bad for my modding experience.
Does anyone know how to make additonal parts/technologies only available for specific races? or only human player? (like specific units in civ4?)