I had a '95 GT that was the automatic. I put a shift kit in it which helped it alot! It was bone stock except for the Flowmaster mufflers(so not much added HP)and it was no problem for it to chirp the tires into 2nd. It was VERY firm shifting.
My '06 is also the automatic. With just the tuner, it has made a tremendous difference in the way it shifts as well. In stock form, there was no way in hell it was going to chirp, except off the start(wouldn't fry them). Now after adding the tuner and bumping the shift pressure up just 5% has made it able to burn them pretty good off the start and will chirp 2nd. Shifting isn't that hard under half throttle, after that though it kicks pretty damn hard. I know when I was at the track and was WOT the whole time, every time it shifted the car jolted and the rear end squatted! That was an awesome feeling
I have read that the new autos aren't as strong as the previous ones(internal parts), but that it's gain is an extra gear. This comes in VERY handy when adding more gear to the car. With 4.10s, I can still cruise at 80 MPH @ 3000 RPM. That is very tolerable even on several hour long cruises

When I either get my Jetta(no fun to drive now that I have the Stang and motorcycle)fixed or get a replacement DD, I wouldn't hesitate putting 4.30s in her!
Bottom line...if shifting at your will is your thing, stay away from the autos. I do have to admit, I'm not regretting the purchase of the auto...yet.