Hello, I have a 2011 IS250, and I am replacing the amplifier (pioneer), with an aftermarket unit. I have a diagram for the pin outs and everything makes sense In terms of the speaker outputs. But there's one part of this that doesn't make any sense to me It has to do with the M.O.S.T. protocol and how the audio feed makes it in from the head unit. I have attached the diagram for reference. Reading about the protocol data communications in the vehicle occurs on a ring network, which I understand in an abstract sense. I also understand that the audio feed from the head unit travels along this ring network. But I'm having trouble understanding the pinouts for the most connector and what to do to preserve the ring network while also pulling the audio feed.

Any ideas on how to put this in place? The connector I'm referencing in the diagram is all the way at the bottom.