I just checked the rocket pods thing. Since they do not work versus fighters, and most of the AI have LOTS of fighters, then it would be better to have a combination of some with rockets and some with PPB3. The ones with ppb would be most useful versus fighters since there is no phased shield for fighters. When carriers and fighters are present the rp will go after the carrier while the ppb engage the enemy fighters. Also the value improvement plants stack, but the absolute max is 250. So to get 150->250 in 60 turns you need 100/3x6= six value improvements. Not worth the slots and build time except on a sphereworld that has 100/200 facility limit.