do a deckplate mod. Instead of spending $200 + on a plastic tube w filter attached, do this. Its easy, and does show noticable power. (not tons, but enough to know you did something.) I did something similar to this. I pulled out the elbow in the filter box, and just made it a straight shot for the air instead of having to go through those tubes. The only thing i did diffeently is not use the deckplate to cover the hole. (im not gonna go mudding everyday, so it shouldnt be a problem for me. Noticable power and cool sound.
http://www.yotatech.com/~corey/tech/techpage5.htm
-Adam-