I bought an 09 YZ450 last summer and it had a K&N filter in it. I want to go back to a stock/foam air filter. I don't like the K&N, and I want to always have a extra dry, clean oiled filter ready to be installed after each ride. My bike has a foam seal on the inside of the airbox where the filter mates to it. No cage. Sooo what I need to know is, what all parts do I need to convert back to stock/foam air filter set up.