As an example, have a look at RESEARCHSUBJECT_SHIELDSTECH1.entity
You can say double the max shield points gained per level of research
researchModifier
modifierType "ShieldPointsMaxAdjustment"
baseValue 0.000000
perLevelValue 0.050000
change to
researchModifier
modifierType "ShieldPointsMaxAdjustment"
baseValue 0.000000
perLevelValue 0.100000
by the way "0.050000" is 5%
Further, you might like to double the number of research levels i.e
MaxNumResearchLevels 2
change to
MaxNumResearchLevels 4
Other things you might like to try are changing research costs or research time.