More than just a one simple change required, if you want the ATX too make pass 100k miles.
I've had TSB 98-13-11 done to mine when new, intermittent 1st-3rd that was so hard it would bounce the dashboard.
That required Different Servo and many lines of programming patch. And it still gets confused???
Look into TransGo's upgrade kit instead. http://www.txchange.com/sk.htm It's been engineered for quicker more positive shifts. This is mechanical/hydraulic only. so I've been told.
Still the components will only handle minimal horsepower. Ever see our ATX out of the vehicle on the garage floor? My John Deere lawn tractor's Hydro almost as big.
I have a cousin in the transmission business and says this ATX has been engineered to just meet the factory output and that's questionable.
Raising pressure makes it worst and shortens life by Oh let's say by 80-90%.
Remember cars are engineered to meet the companies bottom line, so if you want to race, someone going to have built one from the ground up. Majority of ATX's are designed this way, nowadays, it's all about the bottom line.
Terry Haines???? $50k-$200k enough for one prototype?

Paul Echelberger
N8BUU