How much power are you putting down?
I would go with a nice 4L60 as long as it can handle your power range. The 4L80 is a beast, but heavy and will eat more power then the 4L60.
2002 Z28 A4
G5x2, Pacesetter LT/TSP TD Bullets, P&P TB, SSRA, Lid, PT4000, 3:73, 17x7:11 Billet Specialties Street Lites w/ 315 Toyo TQ Drag Radials. 150shot in the works...