First thing to do without even looking at the tune is to use SSpddemon's A4 Trans worksheet (it's stickied) and make sure all the up/downshifts are configured per his logic. It makes the transmission not "think" or wait between TCC unlocks or downshifts, just operates smoother IMO. Then you can use it to overlay the 4th TCC lockup curve with the 4->3 downshift and configure to your liking.