Well, I think you're on to something... it was most likely due to the wheel/tire change. But the reason has to do with weight, not a tune.
According to this: Drag Wheels Rims Weight
those drag wheels were ridiculously light. (a good thing)
The consensus is that the 2k rims are near 30lbs each: http://www.stangnet.com/mustang-foru...thread.285393/
Spend some time learning about rotational mass and you'll understand why you feel a hesitation that wasn't there before.
The only time a tuner is required is if you're changing the overall diameter of the wheel/tire size from stock; and it's only to adjust the speedo so that it is correct.
2014 Mustang GT Premium (deep impact blue)
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