I just picked up the K&N Filter and had it installed last week in my 04 AT w/ less than 10k miles. The manufacturer advertises that you get an MPG performance increase and I hear I should also see a noticable HP increase.

Has anyone had any measurable results? Did it take time for the computer to work well with the new filter? Any other observations?

http://www.knfilters.com/filtercharger.htm

 

This is called Marketing and a true form of pure hype.