Interesting website.
Made me look around for HiFlo filters...
http://www.webbikeworld.com/motorcycle-oil/ (http://www.webbikeworld.com/motorcycle-oil/)
http://www.tobycreek.org/oil_filters/hiflo303.shtml (http://www.tobycreek.org/oil_filters/hiflo303.shtml)
Cheers, Gareth