A/C duct vent cover plates modified for better air flow

[Jiro]

[Jiro]

Just now, Jiro said:

My A/C just went out costing 9K to repair, r410a units replaced R22 ground unit and furnace/condenser. 
Veteran A/C man indicates metal attic ducting although insulated is not as efficient as the plastic insulated ducts, as it retains heat. Also to adjust old more restrictive vent plates without buying new ones, simply bend metal fins to 90 degrees to ease airflow.