Single turbo on dual exhaust

Sorry, I have been out of the loop, but it appears others are chiming in.

Prine's diagram is spot on, the only difference is the down pipe after the turbo would go under the car, and using the Y pipe I pictured above, would split from the one single down pipe into 2 pipes, to join the existing dual exhaust.
The picture you posted in post #10 is exactly what I have in mind. Where the exhaust crosses over to join the drivers side is up to you, but you are on track.

The beauty if it is all the tubing can be done in mild steel, and can be built with (relatively) inexpensive mandrel bends, chop saw or sawzall, and tacked or finished welded with a (relatively) inexpensive mig welder.