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.