ok i guess i can help you here
i have a tiptronic r34
my exhaust is kinda (well very) loud (its a 5zigen miracle fireball), its very light and sounds pretty good (personal opinion) and is the reason why i put up with it.
in auto mode, it sounds deeper and more contained (the shifts arent held as long)
in manual mode, it sounds better, the longer shifts i guess makes the exhaust sound like its suppose to (doesnt make sense but i think u know what i mean)