I was just considering purchasing a kit from Air Force One for my 2000 5.4 and I was wondering what ya'lls opions were. Is this better than K&N? What type of gains can I expect? Thanks again fellas.

 

They give similar results. Vendors that sell the AF1 claim that it adds a tad more HP. I still prefer the K&N due to less heat soak on the plastic vs metal (this is why the factory uses plastic). 12HP or so is generally claimed. 10 is probably more reasonable, but this is a substantial gain for the $$$.