Single turbo on dual exhaust

The exhaust will need to leave the engine through the heders/manifolds into a single pipe that will go to the turbine inlet through the turbo and out a single pipe and then split in two and reconnect to your existing system. Just like the old picture you posted. I would use the shorty headers like Maddart used and then use a T04 turbo and give it 10-15 pounds of boost and meth injection to intercool and raise octane levels. This combo on a 318 would yield low 11s in an abody. I actually had this very set up on a car before and it was killer.