Getting a tune or tuning the car yourself is the answer. The drive by wire throttle curve (and TM) is robbing you of the throttle response you desire. When you push down your foot 25% you are not getting 25% at the throttle blade as the electronic throttle is not a linear curve like a cable system often is.
This is done to make the car easier for people to drive in the rain/snow and prevent sudden throttle jerks or surges when you are slowly rolling through a parking lot in 1st gear. The same issues are found on most Caddys, Corvettes, and even on my Silverado SS with the ETC (Electronic Throttle Control). For some odd reason to me it feels like the GTOs have the worst (slowest) throttle curve I have driven when you step on the throttle just off idle. I'm sure glad my Camaro SS doesn't have that problem.
I use EFILive to tune our vehicles and there is an ETC table you can adjust which will greatly improve the throttle curve making it much more linear and responsive. My Silverado SS now has a very sensitive (punchy feeling) throttle with just a retune of the PCM. I may have gone too far as it can be tricky to drive smoothly through a bumpy intersection but the throttle response is CRISP to say the least! :turbonaug I may have to reduce it just a little this winter for driving in the snow but I am loving it now.
The TM is reducing the timing right off of idle (it actually goes negative for a second in the GM trucks) to the point that the initial take off feels sluggish as you have commented on. Reducing the TM or removing it all together will definately help but the throttle curve reprogramming will help the most with around-town throttle response.
Hope that helps!
Greg

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