Interesting twist to all of this -- my voice command (the Sneezing Man button on the steering wheel) plays at a normal volume levels. The Nav instructions (when they cut into the music being played) are at a much lower level, as is BT calls.
This isn't an issue of the crossovers to the tweeters being wired wrong. Taibnal hit it on the head- the Alpine retrofit kit is neither Stereo or Hifi (in coding-speak)-- it's a mix. Coding just the PDC or BT or Nav volume codes all of the values that way, i.e., e90_hifi in Nav to e90_stereo will change all volume levels to e90_stereo.
I've pretty much resigned myself to the fact that--
1) BMW *knew* of this problem,
2) they should have never sold the Kit in the first place,
3) The 'fix' for it is to never install it in the first place, and to go with another solution
4) There is no coding fix that produces ALL of the items working at the same time via NCSExpert or INPA/P-- although there might be something else that might work...
Grumpy in South Texas.