I had an '03 SS Silverado for a bit as my test n tune vehicle for work. I had a magie supercharger re-geared with some rather large injectors to cool down the CC. I dynoed it at 620 rwhp @ 10.1 psi of boost and the front driveshaft removed. I towed some really big boats with it, I would not worry a bit. I would however be leerie of the transmision, I believe you have the 4L65E in there and I toasted like 3 or 4 in less than half a year!!!

See if GM offers a cooler that will not void your warranty, if not I would for sure be installing an aftermarket and adding a little fluid. One added bonus of this is the extra fluid allows more heat removal from the system along with the temp drop across the cooler. I will not run any late model tranny w/o one. That said, I also run a fan on mine since these newer vehicles have e-fans you need something cooling the fluid when you are moving too slow for the H value across the radiator to be effective.