I am not sure if you have done anything yet since it has been quite some time since the last post.
I have a M3 2011 with the upgraded Dirac system and it still doesn't sound all that great. I found one company that specializes in BMW called Bavarian Soundwerks ... www.bavariansoundwerks.com
You might want to look into them. I intend to upgrade my speakers as a stop gap for now as I don't want to do a rip and custom install. They are coming out with an amp upgrade soon I understand.