Actually I did use a Fernco coupling from my shop, reason being the rubber matrial use to make these due to pressure ratings is a lot thicker than the cheap **** you buy from an auto parts store, so that it will support the filter and hold up more, and to each his own I guess. And if you want your stuff clean, don't hack it by just putting a filter on the end, spend the money and buy an intake, then it will look clean