look in the file RESEARCHSUBJECT_STARBASEENEMYORBITBODYBUILDRATE.entity
the lines you are looking for are
researchModifier
modifierType "StarBaseBuildRateAtEnemyOrbitBodyAdjustment"
baseValue 0.000000
perLevelValue 0.250000
artifactPicture ""
at the end of the file, the bolded number is the build speed modifier for vasari of starbases in enemy gw research
you just have to create a mod folder, put the entity inside a gameinfo folder under the mod, then alter the number which I think might be percentage buildrate increase, copy the entity.manifest to the mod folder, and play
harpo