We are still in the testing stages, but it is working great. I was using a Merv 8 which was creating 940 CFM at the nearest vent and 715 CFM at the farthest vent.The Merv 11 is creating 940 CFM at the nearest vent and 702 CFM at the farthest vent. Better filtration with little loss of air flow (CFM), a win win in my humble perception.