Wiring diagram and amplifier location for the BOSE audio system needed?

There is no single amplifier in that system. Each speaker has it built into the speaker "module". Also, there is no radio in the dash. The display is just that a display. The actual radio is in the right rear of the trunk. To get anything to fit up front is a pain because you need to cut out part of the dash support to get room behind it.

Good to hear. Be sure you don't use speaker level signals to feed the OE amps. They really don't like that and will destroy themselves in a very short time.

I generally just add in a BT board with two way capabilities into the stock unit. Easy to do on GMs (and most others) especially these days. Also not hard to add aux jacks but then you need to add in signal converters to prevent someone plugging into it with speaker level outputs. Or there are modern units that have all the toys but look like OE units, Ecklers and others sell those.