Well the 2013 mustang throttle response must be amazing cause mine is lacking. I also have an auto. Idk if u may have a manual and that may make a difference in response.
If im driving at 10% throttle and put my foot to the floor as fast as I can, the car responds right when my foot hits the floor. There is less then .1 sec delay. Its as fast/faster than any other car I have had.
My '13 doesn't seem to have any lag in throttle response either. Perhaps they made a change to the programming on the new ones.
I've gone back and forth over a tune and it's not worth shortening or voiding my powertrain warranty. 420 factory HP is still a lot and yes I understand that we always want more, but to me the risk and voided warranty doesn't outweigh the small gain.
I think like that as well which is why I'm looking at the procal tuner. It keeps the 36000/3year warranty. It doesn't really give a whole lot of power on the top end, but there are numerous dyno graphs showing around a 40rwhp jump in torque between 1500-2000 rpm. Which, in my opinion is where the car needs it the most because the factory tune leaves a bit to be desired. And not to mention the throttle response. Like mentioned above there must have been some sort of revision with the '13