With all this effort, why wouldnt you just install an aftermarket amp and get better sound? I bet there will be a little bit of an attenuation problem and/or some some floor noise coming through the speakers.

I have installed several of the Kenwood 419's and they look cool, work ok, but the Bluetooth is absolute crap, so much so that I have had customers say they dont even use the BT because its just that bad.