This is in reference to a relatively new home in the south, ~4 years, but I've only lived in it a short time ~6 months. The system has a filter before the blower, no filters on the air intakes around the home but oddly had these felt pad sheets in the exhaust grills, the things the cold air was coming out of just to be absolutely clear. They were slightly discolored but I'll guess they've never been replaced or cleaned in 4 years of constant use so they didn't seem to filter much. The material was relatively dense and I decided to remove some of the pads from rooms that felt warmer even with the vents full open and it seems to have easily increased the air flow by a factor of 2 to 3x. Now I'm wondering if this was a safe or good idea. Since the system does have a filter right before the blower, I assume the cold air coming out is relatively clean and doesn't need filtering, and the pads were just causing excessive air flow restriction but I can't be sure. I've never lived in a home with central AC so I'm not sure if these types of pads would be normal, or recommended, or whoever installed this system was just doing something odd. (There's been other things around the home that I know for a fact aren't quite 'standard' so I wasn't sure on this). Thanks for any advice or input.