Im running COS 3 (03190003) on my 2003 Tahoe and would like to go to COS 5 soon. Planning on using the nitrous options to pull timing for towing with the Turbo. That way i can dial in my timing for playing/racing and when i want to hook up the trailer i can flip a switch and not have such an aggressive tune. Engine has had a turbo (Usually 6-15psi, accidently hit 30psi 3 times) on it for the past 225k miles in my silverado and now 35k miles NA in my tahoe so i want it to last a little longer.

I still have to do the 4L80E swap so im not in a hurry for the COS 5 upgrade. Would like to know the proper way to do the upgrade.

Thanks,
Jonathan