If I can get 12.5L/100km with a GT3076/GT3040 turbos around Sydney then you are either the biggest lead foot in history or there is an issue with the car.
The turn flow is hardly going to be an issue on a sub 270rwkw car.
The air has to turn at some point and you are reluctant to cut a hole in the other side of the engine bay so whichever way you cut it a Blitz cooler will meet all your needs.
Disco, buy a cooling pro or a Blitz turn flow and be done with it they bolt up to factory piping and you can get it tuned once with all the fruit you need to get the best result.