This is the answer
https://5series.net/forums/private-m...ilt-loc-99857/
I used to own an E60 M5 with a Dirac audio system in it. I also had another e60 with a Logic 7 in it. BAck then I had purchased 2 different wiring harness from a member called technic. These harness would help you tap into the audio system to draw an audio signal that can be used for an aftermarket amp hook up.
I found the wiring harness that I had from the Dirac and wallah ( plug and play)
The link I am showing above is for the Logic 7 harness but the point is that technic was selling these harness back then for the Dirac e60 M5's that I reused in the F10 and it works like a charm.
I will try and post pictures as I still have to put my trim back for the most part.
I have added a JL audio 12W6 v3 D4 in a sealed box that I built myself and the sound is truly AMAZING with this addition.
It's nothing of the nature that a bass junkie would sound with vibrating his entire car but it's just clean punchy bass where it was missing.
Is my setup an overkill.... probably but it sounds just fantastic per my taste.
Pictures will be posted later as I don't have any at the moment.