Re: GT Blackline
It pretty much depends on the dealer. I bet most of them would say no, or that they won't offer warranty on the car if the Q2 is installed.
But anyway, the only difference between the Blackline and Q2 is the interior color(only the black leather seats with red stitching is available on Q2) and wheels(different style, both 18"), as far as I can see, it would be easier to just change the wheels provided you do not want a different interior color. Not to mention, the Q2 has a wider choice of paint colors than the Blackline, and I think the interior is the exact same(black background on instruments, with white light and red indicators, darker central console color, aluminum gearshift knob and aluminum pedals, etc).