Technically speaking, if you opened up the exhaust and added a fuel controller at the same time, you would see marginal gains, but nothing worth spending the money on a K&N for. The factory filter in the wolverine is actually quite good, I would stick with that just for ease of use if nothing else. I have not researched the effectiveness of filtering in a K&N vs an ATV oiled foam filter, however for streetcars I am very familiar. K&N's do not filter as well as a stock paper filter in a car or truck, as the holes in the mesh are larger, so they let bigger particles through. But in the same token, they let more air through as well, which is where you see the HP gain. Still not worth it to me.