I am looking to get an air intake system for my 05 F-150 with the 5.4.  I am looking at K&N, Airaid and the one from Roush.  Does anyone know the advantages/disadvantages of each system?  I have tried to do a side by side comparison online but I can't really find out the differences.  I want the one that has best gains.  Any information would be appreaciated.  Thanks.  

Have you considered an AEM Brute Force? They have oil-free filters and are supposedly easier to clean than the oiled filters like K&N and Airaid. Not saying they're bad. I have a K&N myself and have been happy with it, but I do know the flow on the oiled filters tends to deteriorate as they get older and you wash & re-oil them. Supposedly the AEM dry filters have more consistent flow after prolonged use. Just what I've heard.