It seems to me that if more noise is created by installing the foam filter, it should be flowing better/more air. Like exhaust systems, some make more noise and do produce better flow, however some just make crappy noise without any apparent gain. How’s that for contradicting my own logic?
My guess is that the foam filters may produce a smidge more flow at the expense of less particulate filtration. I also question the foam filter’s durability over K&N-type oiled filters.