Steve, your time and speed is almost identical to my G8. I have the same issue in the middle too. What kind of 60 ft's are you getting?
Are you on street tires, or have you added some DR's for the front? That solved my Flex launch issues by cutting spin on front. Of course it may be more needed on Flex as most of the weight difference between SHO & Flex is in the back, where it hinders by keeping rears hooked up, and allowing fronts to spin more which frequently caused my TC system to shut car down to prevent AWD damage.