I'll contribute my personal experience with CAIs on the 04 and 06 F150 with the 5.4L engine. I had the 3in. AF1 on my 04 and it caused horrible drone as well as never ending check engine lights. The AF1 had to go. Next I tried the Outlaw Power intake on my 06 F150 for a couple of months and about 1,000 miles. I had no problems with it other than the intake resonance noise that it produces at certain RPMs. Unfortunately, it makes that noise constantly when towing our travel trailer so it had to go. Nice throttle response and I picked up about 1 MPG. Just couldn't put up with the noise. Some people like the noise, I didn't. Your mileage/results may vary. My personal conclusion is that after market CAIs on the NBS F150 are more trouble than they are worth. The stock intake IS a CAI and it is butt ugly but looks fine with the hood closed. The best modification I have found for it is the DWV intake mod I put together for my 04. It replaces the snorkel tip with a 3.5" piece of black ABS going into the stock fender hole for less restriction. I think Bill and I came up with this idea at about the same time so I can't claim I am the first person to think of it. It does work well and Bill has actually dynoed it and it has a gain of 7 or 8 ponies while still keeping the intake drone quiet. That and an AEM Dryflow replacement filter is what I roll with now.
Man, what a first post! I need a nap.
