I have always used the Honda 15400-PCX-004 filter on my 2003 S2000, due largely to opinions on S2KI. High flow and metal on metal seating have always been mentioned as key characteristics. I was so impressed with the NAPA Gold I just pulled off my 92 Accord that is got me wondering if it would be a better option. The Gold was very sturdy and the ADV particularly effective. Here are some shots of the PCX internals.Credit and thanks to 90crvtec for his work.
http://www.s2ki.com/forums/index.php?act=module&module=gallery&cmd=viewimage&img=409176
http://www.s2ki.com/forums/index.php?act=module&module=gallery&cmd=viewimage&img=409163
http://www.s2ki.com/forums/index.php?showtopic=473347&view=findpost&p=10104759
http://www.s2ki.com/forums/index.php?act=module&module=gallery&cmd=viewimage&img=409176
http://www.s2ki.com/forums/index.php?act=module&module=gallery&cmd=viewimage&img=409163
http://www.s2ki.com/forums/index.php?showtopic=473347&view=findpost&p=10104759