First of all make sure the A/C in running efficiently. Take a temperature measurement at the filter ( Return Air ) and at the closest supply register. Ideally the difference in temperature should be between 17-18 Degrees. Second, make sure and check all the duct work, transitions, and plenums. ( Anything the ducts connect to ) you want to make sure your not loosing any cold air in the attic. Insulation and a Radiant Barrier are a good idea. Btw, why did you insulate above the garage ???? Is it a conditioned space??? Jack P.S. How old is the house? What type windows?
