I finally have gone past 1000 miles on my new '05 auto XT. I stayed below 4K pretty faithfully and never went full throttle. Now I have and I am impressed! My other vehicle is a 2002 4.3 litre auto std cab Chevy S10 with JBA headers, Gibson Catback exhaust, a K&N Intake, Superchips tuning, and a 4.10 posi rear. The S10 has been to the strip and is good for around a 15.25 qtr mile (altitude adjusted). I didn't expect the XT to be much quicker (the S10 is actually a little lighter than the XT). I am happy to report I was wrong, at least at this altitude (3250 ft.) The XT is 4-5 mph faster at the approx 1/8th mile mark of my personal usually deserted interstate on ramp proving ground. I love the 4.44 rear end. This thing really pulls in first gear, and after a slight lag when shifting to second pulls hard thereafter. The question in all of this is: does the AP 1 do away with the hesitation and the first gear to second gear shift? The tranny is shifting itself. I'm not manually shifting it. Thanks for any input!