I want to install an extensive aftermarket SQ stereo into the car (amps, DSPs, speakers in alternate locations), but I want to keep the stock nav/bluetooth. I know it is possible to do this, but my concern is the handling of bluetooth calls by the stock system. Specifically, the new system is going to be much louder than stock--does the bluetooth function have a separately maintained volume level so that phone calls play back at lower volume than music?

Also, I have seen in a previous post that the stock bluetooth plays through only the left door speaker. Is that true? With an aftermarket system, that would end up playing through the whole left side of the car. Will that screw up the functionality of the stock bluetooth microphone?

BTW, yes I have searched.