The snorkel with a filter on top is the cheapest way to go. There are also pre-filters like KWT and S&B. I went with the KWT. From Honda Bobs excellent photos, you remove the black resonator (crazy looking black tube with roundish chambers).
The KWT can be mounted anywhere, so I wanted it out of my way not blocking my rear view. Great if you have rear a rear window. I mounted it backwards behind the passenger seat. It doesn't require electricity and it makes no noise. Dust is separated from the air by cyclonic action. The dust settles into a dirt collection chamber and the cleaned air goes to your air filter and plenum.
I have been testing a pre-production model X2 and just got the production model. Here is my review at 1400 miles, check out the video. If you want more info just search this forum typing in KWT, to see what other members said.
I just got my production model KWT X2 pre-filter, so time to look at how the pre-production model has performed. Here it is with 1400 miles on the filter.
hondasxs.com
KWT Filters particle separator revolutionary cyclonic technology separates particles and dust before the airflow reaches your stock filter. The KWT separator requires no fan or other moving parts. Installation is quick and easily done with basic tools.
www.kwtfilters.com