If you want to keep your warranty I wouldn't install any tunes. If you flash the ECU or TCM with EFI Live it will leave a signature so the dealership will know about it. Some tunes will remove the safeties or alter the protocols which could damage something if over-used.
Even installing a catch can, or High Flow Air Filter which is can void your powertrain warranty.
You could always get a refund for the cost of the extended warranty, and install the tunes and upgrade at will.
Emission Control System Limited Warranty
For light duty trucks, see “How to Determine the Applicable Emissions Control Systems Warranty” under Emission Control System Warranty in your Chevrolet Limited Warranty booklet for more information. Defects and performance for car and light-duty truck emission control systems are covered for the first 2 years or 24,000 miles, whichever comes first. From the first 2 years or 24,000 miles to 3 years or 36,000 miles defects in material or workmanship continue to be covered under the New Vehicle Limited Bumper-to-Bumper Warranty coverage. Specified major components are covered for the first 8 years or 80,000 miles, whichever comes first. Defects and performance for heavy duty truck emission control systems including those found in 6.6L Duramax® Diesel Engines are covered for the first 5 years or 50,000 miles, whichever comes first.
- California: Defects and performance for cars and trucks with light duty or medium duty emission control systems are covered for the first 3 years or 50,000 miles, whichever comes first. Specified components for cars or light duty trucks equipped with light duty or medium duty truck emission control systems are covered for the first 7 years or 70,000 miles, whichever comes first. Defects and performance for emission control systems found in trucks equipped with 6.6L Duramax® Diesel Engines are covered for the first 5 years or 50,000 miles, whichever comes first. Specified components for the emission control systems of 6.6L Duramax® Diesel Engines are covered for the first 7 years or 70,000 miles, whichever comes first. Some California emission vehicles may have special coverages than those listed here. See “California Emission Control System Warranty” in your Chevrolet Limited Warranty booklet.