the only upgrade i know of is switching a 1.8T tranny to a 2.8.
I've heard of some cars having the solenoids and springs replaced... but i havn't heard anything of audis doing this... nor do i think there's much benefit. if you're wanting your tranny upgraded... you chip it
GIAC has one but i havn't really heard anything about it. $250 isn't bad if it has noticible gains. I can see more agressive shifts being a lot of fun, but I don't know what you're gonna see on the 1/4 mile.