I put a 2" leveling kit on my 2002, I went the hockey puck route from Fat Bobs Garage and IMO it was very much worth it. My only problem was, when I did it I still had regular street tires on the truck and it looked goofy until I put the 33" Terra Grapplers on.
Here are a couple of bad before/after pics from when I put the kit on:
You can look through my pics on here, Im sure there is a better one somewhere in there after the tires and everything.
As far as the CAI, Ive never done one because I work in dusty conditions and the gains from one is almost nothing without a bunch of other mods, so I run the paper filter instead of risking my engine being ruined from the dust just to have a cool sucking sound on throttle.