I just bought a set of 28mm PWK's and my old K&N clamp-on's don't fit. I would like to know if there is a place to get them fairly cheap. I bought my last pair form Rockymountainatv.com for $60 but they don't offer it in the size I need. Any ideas? I ride 90% sand so would the K&N's be the better choice or would the foam uni-filters be better? Thanks for the help.