Replace your old and dirty air filter with a Drop-In Air Filter for your 2003-2007 Ford 6.0L Powerstroke. An air filter is a crucial component for your engine and its purpose is to keep harmful airborne dust and debris out of your engine. Drop-in air filters get their name from their designn as most have a "drop-in" installation and simply fit inside the factory air box. Shop for drop-in air-filters from manufacturers like S&B Filters, AFE, K&N Engineering, and others available at XDP. Direct-replacement drop-in filters are manufactured with a paper filter media, and aftermarket filters are made with an oiled cotton-gauze, or synthetic dry filter media.