I have the K&N intake and after three years of running it, with a pre-filter, I switched to an Amsoil filter. I have gone through two K&N airfilters with no problem as far as dirt entering the system in about 60k. , but decided to switch to the Amsoil about a month ago. With the K&N filter, I saw a max of 28-29 lbs of boost with the stock boost elbow. Now I see 35 lbs of boost with the Amsoil filter, same setup. I never had a problem with the K&N filter and don't have enough mileage to judge the amsoil, but i'm pleased so far.