Below is the reply I recieved from K&N filters regarding the article about their air filters found at www.cycleinfo.calsci.com Who's right? at this point I have no idea, just thought i would share what I know to this point....Happy motoring!
I appreciate you bringing this issue to my attention. I see that this "message to John" has been passed around on the Internet for years. I'm surprised I haven't seen it already. At any rate I believe it is a total fabrication. I can not find any evidence that the study was real or any information concerning the message's origination. K&N, as our website indicates, tests our products both internally and via independent laboratories and we stand behind ALL of our claims. If you can find the original source of this study I will investigate it further but I believe this was a clever way for someone to get their message passed around just like bogus e-mails concerning taxing e-mail and other false claims about businesses and products. If there were true studies that showed these results, there would be people or businesses that would stand behind the results instead of a nameless person claiming to have been part of the study. Also the link you sent doesn't work. In fact no one owns the domain name caslci.com as far as I can tell. If it is mis-spelled please send me the correct link and I will look into it. Thanks,

Mike Garner
Systems Development Manager
K&N Engineering, Inc.
909-826-4000 ext. 4040
www.KNFilters.com
MikeGa@KNFilters.com