Most CAI are kinda like hot air intakes because some expose them to the engine bay heat.

This is just preference here but I'd go with the Airaid Intake Tube and just mod the stock airbox for more airflow. This way it keeps gathering air from the fender where it's much cooler than the engine bay and will not heat soak as bad. If you cut the front (side) of the airbox out it gives it a lot more room to suck in air.

Other stuff you can do all depends on your goals. A custom tune really wakes up the 6.2/6L80e if the person doing it knows what they are doing. Go further is exhaust, cam swaps, supercharger/turbo etc etc.

 

X2. I use the airaid tube on my trucks with modded stock air boxes and green filters. They seem to work very well.

 

 

Google green air filter usa. I use them on everything.

 

 

Airaid intake tube and AEM filter in stock air box for me. I saw a small air flow rate increase at wot but not much seat of the pants difference. I do like how the tube cleans up the engine bay though.
I agree with the tune comment above primarily for drivability improvements. I don't feel like my Denali makes much more power but it is much more responsive to throttle input after tuning than it was stock.

 

I use the Airaid Jr Kit, which is the Intake Tube and a drop in dry filter. I prefer to use Dry Filters because I have heard of issues with oiled filters messing with the MAF Sensor.