a dished head header assembly for a heat exchanger having a containment body that includes a rounded , or dished , wall portion forming an interior cavity . a flange attaches to the containment body and fastens the header assembly to the heat exchanger . a plurality of refrigerant passageways are extended through an opening in the containment body into the interior cavity . at least one baffle is attached to the rounded wall portion . the baffle divides the interior cavity into a plurality of sub - cavities . at least one divider divides the sub - cavities into a plurality of chambers . the plurality of passageways includes an inlet connection and an outlet connection for a plurality of refrigerant circuits . each passageway is disposed in a corresponding chamber of the plurality of chambers . extensions into the headers with diffusers insure efficient operation and performance of the heat exchanger . the adjustable flow restrictor plate maintains optimum velocities to further enhance performance .