I think if this focuses more on the powertrain aspect...it's not a repost.
Aren't engines typically rated at lower numbers in trucks as opposed to cars? Like the LS2; It's rated at 390 in the Trailblazer SS. Soooo...I'm thinking that they aren't detuning the 3.6L to ~280hp for the Camaro, because the CTS is closer to Camaro's size than the Lambda vehicles, and has it's DI 3.6 rated at 302hp.
My 0.02.