I know an H3 owner "WhiteH3"(his - Elcova H3 Forum name). He's the first to have a K&N Air Intake kit installed on an H3. K&N's R&D department installed it for him and did some dyno testing too. I'll contact him so that he can post some pics and dyno charts, etc. However, you may want to check out this webpage on air filters. It's technical but very informative...
http://home.usadatanet.net/~jbplock/ISO5011/SPICER.htm