Installed Volant Poweflow intake. HUGE difference. I also have the 5.3l vortec but on my 03.
BEFORE:
AFTER:
I opted for the Volant over the other companies for a few reasons. I like the idea of having the sealed box. Theyr box restricts the engine bay heat, but also has three cutouts on the side of the box. One going out to the fender (this is the same as the factory inlet). Second goes forward which basically draws the air from behind the headlight. Third, there is a 2.5-3" hole in the bottom of the box that draws air in from under the truck. They sell a kit that mounts to this as a ram air setup, i opted against that. Being a pickup, i might have times where i might see a little bit of water and i wouldn't want the worries of hydro-locking (again). Above all, it installs really clean and looks great under the hood.