[Number 3]

Tune and Ranger both technically void your warranty. Anything that interferes with the cars calibration would be deemed to void the warranty. We know GM can detect a recalibration. We don't know if they can detect the use of device plugged into the OBDII port that alters the programming.

As for why the Camaro SS has cylinder deactivation and the SS doesn't is probably more around the expected volumes. The Camaro was deemed to NOT need a GG Tax. That necessitated cylinder deactivation. The SS is lower volume by definition and GM probably accepted it like they did on the GXP. Imagine the threads back 3 years ago if the Camaro had a GG Tax and the Mustang did not.