colder air is always better, the problem with some "cold air" intake kits is the metal tube gets very hot under the hood that it warms up the intake air. you can tell cold air is better when you look at track results for various cars. the times vary a lot depending on outside temperature and humidity. The stock setup is just fine unless you plan on flooring the Tahoe all the time.

 

Cold air is better for efficiency cuz the air is denser, more O2. It is really noticeable on a carb car since it doesn't account for air temp. CAI really only show a minor hp improvement at high rpm. The stock setup is basically a CAI w/ a standard paper element. So if you want that extra hp at 5 grand, then just put in a reusable cotton filter but be careful you don't over oil it as it can coke the MAF sensor. Also there have been reports of warranty problems if the dealer sees a oiled air filter.

If you want more hp, get a 2009 w/ a 6.2L.