Came across a thread that discusses the air filter for the EVO 2 kit. Slightly different application but same filter. Thought it might be of interest in this discussion.
I may be wrong here but it looks like they're referring to the filter that goes into the original air box. This kit will replace the entire air box and you use pod filters instead. Unfortunately after my recent trip I won't be going this direction as I crossed many rivers with a few of them deep enough to have water flow quite far over my front wheel estimating them 60-70cm deep. I also drowned my bike when I went swimming in the last one of the trip - but that's got nothing to do with the air box/filter I just remember the entire air box filled with water to the brim before it drained out

Edit- I now see I was wrong it is a pod filter. Nonetheless I don't feel comfortable with that setup for the riding I do.