Moved to Car Audio.
Realistically, you'd be better off posing this question in a BMW-specific forum. Our focus is installing PCs in vehicles.
my e46 bmw's original headunit gives a quite poor performance, i wonder is there a "loudless" function on this original headunit? can improve the performance a bit...
and how to turn it on?
besides that the loudness never does anything to improve performance. If it's poorly performing to begin with, loudness will only make it a louder poor performing system.
change HU. stock isnt good in most cases