I used the Brute Force intake on my truck. I like the fact that it is an oil less filter. Doesn't need to be coated with sticky spray to filter out all the dirt. Is very reasonable price too. Check out streetbeatcustoms.com they match prices.
I've got a K&N Series 77 (metal tube) on my '04 5.4L. The intake definately added some engine noise (more than my Bassani muffler did) and provided a small increase in power. So far I have no complaints with the unit, it installed relatively easily and has required minimal maintenance. I typically will just brush off the filter witha broom every few months. I've been using K&N filters for years so I've become accustomed to the cleaning and oiling required on these filters. As a FYI you do not need to clean a K&N air filter more than once every 10-20 thousand miles so long as you don't do a lot of dirt road or off-road driving. I think in the end most of the air intake systems out there are good quality and will provide the same gains, just do some research on the filters and find out which one best fits your driving style and needs.
I have an Air Raid intake. I had Chux Trucks in K.C. install it. All together was about $250 with installation. Mil discount helps too I like the increased performance. Barely notcied any gas mileage bonus. The increased power makes you want to drive harder, so any gains in gas-mileage you lose in ego.
I installed the K&N model and as stated above I noticed no difference except the engine noise. Power and fuel mileage were not effected. With an exhaust and a tuner maybe it would make a difference but alone it's not worth the $. I kept all my old parts and am seriously considering switching back.
The noise was kool at first but pulling the camper it gets annoying.
I have an AFE CAI on my '05 5.4. It was a little noisy until I lined the box with 5/8" high density foam. Covered everything but the hole in the front with it, and it did seem to make a dif with less noise. used spray adhesive to fasten it. Would rather listen to the Magnaflow pipes but what can you do...