sorry, no auto here, but even with an 87 octane 'gas saver' tune on my xcalII, i can feel a difference in response, pickup (not much of course), and seems to idle better... took me over a year to finally get one once i got my gears done, and I will say that it is the best $400 i ever spent on anything (car related or not), bar none.
I have heard numerous people say that the difference is even more noticable in an auto, if that helps any.