Before getting a CAI, check this out: http://tahoeyukonforum.com/forum/showthread.php?t=14022&highlight=swiss+cheese+mod
Commonly called "the swiss-cheese mod", basically you drill a bunch of holes in your stock air filter box. This allows more air to flow in. I put a K&N drop in filter in there to further allow more air flow. The mod itself is free, you can do it with whatever filter you already have. My truck sounds and acts differently. I can't verify a HP increase, but it has better throttle response and pulls harder going up hills like Turnagain Pass. And it makes a cool, turbo-charger like whistle sound when you accelerate.
