I'd peruse this research on High-MERV Filters and their impact on airflow and pressure instead of taking one HVAC technician's word for it: http://www.homeenerg

I'd peruse this research on High-MERV Filters and their impact on airflow and pressure instead of taking one HVAC technician's word for it: http://www.homeenergy.org/show/article/nav/issues/page/4/id/667 http://www.homeenergy.org/show/article/nav/issues/page/4/id/... This graph of airflow vs. MERV rating isn't very conclusive in my mind: http://www.homeenergy.org/UserFiles/file/26-6_p34big(1).jpg http://www.homeenergy.org/UserFiles/file/26-6_p34big(1).jpg Granted there are about a million variables in all HVAC systems that could affect the results.