I'm 90% sure I'm going to upgrade with Audison. I've been out of the car audio game for quite awhile so I'm not up to speed on the latest and greatest. A local installer that I've worked with in the past on other things recommended a system from these guys.
https://www.audison.eu/
It would be their AP8.9 amp, which has an integrated DSP in it.
2 APBMWKE K4E two way speakers in the front doors.
2 APBMWX4E coax speakers in the rear doors.
2 APBMW S8-4 underseat subwoofers.
I did the HK Bavsound speaker upgrade in my previous M3 amd while it was an upgrade and it sounded good, I'm looking for a much better improvement this time around. If anybody has any experience with Audison products, I would appreciate the feedback. And of course and feedback (pros/cons) on this upgrade would be appreciated was well.