Look forward to more. Will you be done in time for the Rally? You've surely invested a lot more money than I have. Really look forward to hearing your results. I think I have somewhere from $1200 to $1500 total invested in mine. That may go up if I decide to paint this winter, as I was also thinking of a couple other ideas.
I understand the "gain " issues. I believe you ran into the same issues I was having with trying to use adapters or the low impedance/high level inputs of the amp. That was the catalyst for digging in and bypassing/removing the factory amp from the signal chain. Of course, now I don't have any of the factory audio on the bike.