Take a look at this site which pretty well confirms that there is no performance benefits of aftermarket filters like the sellers claim.
http://www.autospeed.com/cms/A_2232/article.html
"We’ve been saying it for years but it’s a message that doesn’t seem to have widely got through. Nine times out of ten, dropping an aftermarket filter into the standard factory airbox is not going to get you any more power.
None.
Zilch.
Bugger-all. "
