Congrats on your ride...good thing you picked the right color
Your onstar install is inspiring. Makes me wanna move mine and put something in that space.
Heres an idea for your chrome that may or may not be feasible. Is it possible to dip your chrome plated pieces into a black nickel that would give it a black or black chrome look without spending an arm and a leg? I saw this done before and thought it was a good idea granted it is a durable plating. This would keep you from having the cheap plastic look but would give you a stealth look.
Black nickel plated brass knob:
Perhaps this could be its own thread.