[FogCityM3]

I did a lot of research on this and there is a tradeoff between letting in more air vs letting in more dirt; AFE dry and Macht Schell oiled gauze have the highest filtration efficiency rating that we know of (~99%, albeit according to their own tests) vs the stock filter (which is 99.1% efficient). I personally went with the Macht Schnell as it has more airflow vs AFE dry. The latter I believe has a slightly higher filtration efficiency rating. Macht-Schnell (made by S&B filters under private label) AFE, and K&N are the only manufacturers that I found give any indication of filtration efficiency. S&B's website (which sells filters for trucks/diesels) has some pretty interesting tests vs. competitors.