Originally Posted by M3takesNYC
Do your poor engine a favor and change or clean your filter more often! If the top side looked that bad, I can only imagine how bad the bottom side was given it really sucks a lot of dirt up from that lower intake cowl. Probably will pick up 15hp from simply putting a clean filter.
The bottom side probably looks great. If you change one of these filters and study the intake box, you will see how debris collects on the top, but falls off on the sides and does not collect on the bottom. And as air filters go, the used stock one in the picture is not bad or clogged up enough to cost 15 hp.