You asked kind of the same question last year http://www.gmforum.com/t278440/
The answers then are really no different than now....it'* not recommended. You are dealing with added stresses from a SC motor to the tranny, and then when you throw on an additional 1000+ pounds on the bumper you're chances of grenading the tranny are increased. The GVW for towing is maximum for the car, but does not take into consideration other weigh additions such as people and cargo.
Motor HP, tranny, rear end ratios, tire size and shocks are all desigined into vehicles that are designated suitbale for towing. It has nothing to do with just motor HP.