Hear is how I solved the air filter problem. My objective was simple make the air filter easy to service an a trip and use the stock air box. The problem with the stock foam filter is it is bulky, hard to clean, and requires grease to seal it up ( messy). I purchase Uni Filter green bulk foam ( bf-1) it is 65 ppi and 5/8 in thick. The after market filters are a courser foam. I then cut out a foam piece the same shape as the stock filter adding 3/4 in all the away around. Oiled up the foam placed it over the air box inlet and bolted the cover on. Since they are just a flat piece of foam they are easy to clean and oil and and don't take up a lot room. I have used this filter for several thousand miles all over Nevada, Arizona, and Moab area of Utah. In dusty areas I service or replace the filter every other day. The bottom of after market air filters sits on the floor of the air box so air can't get through because of this I think my filters surface area is about the same. Because of how compact the oiled foam is when the lid is on no grease is needed.