What are the advantages of the different brands. I have heard that AF1's give the most increase in horse power. Is there another brand that sounds better or has some other advantage? I am trying to figure out which one I should get for my 2001 5.4L. Thanks, Mac

 

I bought K&N FIPK because i got a hell of a deal on it cause i used to do parts. I got an 05 SCREW and it made the engine alot louder. sounds good though, good power over 2000rpm as well. but like i say, i bought it for price, but i am happy with it, just probly gonna get a filter that does not require oiling it

 

For a loud metal open element intake, I would recommend the AF1 or AEM.

For a more subtle deep tone sound and if you want an intake that is sealed to protect the filter from mud and heat, I would recommend the Outlaw Power intake:
http://www.outlawpower.com/productdetail.php?sc=1180

Here is a pic that shows how mud can get onto your filter if it is not protected: