First things first, do you know what year auto box you have, there is a slight difference to the main drive shaft inside regarding the amount of bearings and the oil channels. The series 1 box's have serious oil flow probs, and over heating probs. But you can get around this by fitting a series 2 main shaft and bearing assembley, (not cheap). Then the next prob will be the clutch plates, there are only a few places that you can get the slightly heavier duty ones. Then there's the T/converter, you can have a billet one made to your spec if you want (ie, nothing happens untill 4000 rpm, then it kicks in) they do this mod on the top drag cars. You can also play around with the hydraulic valve block and slightly raise the oil pressure to give you a more solid/positive gear change, (HKS done a thing called a ALC, automatic line controller). There is a box on the market called a level 10, a few guys in Holland have them and swear by them, do a google.
Have fun, it has taken me 9 months to build mine to the way i want it.
