the crazy thing is he was granny shifting and the car is still spinning off the line so i think it's possible to pull 2 to 3 more tenths out of it. and then even crazier a 75 shot could possibly put it in the 10's.
Correction. A Cat Back did next to nothing for the previous N/A 4.6L cars. These new 5.0L's are making a whole lot more power and have ability to walk it out to much higher RPM than the previous modulars. So I would imagine quite an improvement could be made by freeing up exhaust flow. Look what cat backs have done for the previous '03-'04 Cobra that were in the now new GT's power range? Or even the new GT500's? Seeing power increases of 40-80hp with exhaust and tune were not at all uncommon with these cars....and these new 4-Valve heads outflow both those castings.
I'm just going to have to remain skeptical until these cars really hit the streets and there are others out there getting similar results. I just find it very hard to believe that Ford put this much engineering into one of the best performing engines of all time, only to leave ~40hp on the table with a simple muffler swap and tune.