I have been using the Fram Air Hog now for about three years and I must say I can't tell that much of a difference and I also couldn't when I used K&N. I can see using them for cold air intakes and such but I don't think it make much difference in standard applications and in some instances may be bad example letting dirt and fine molecules through to the engine. I have two of them and I think it is more of a hastle to clean them then it would be to just go out and buy a new one every 12k miles. Let me know what you guys think but I am thinking once these are worn I will likely go back to standard filters.