Turbo charging off topic

I'll toss in a monkey wrench.
If you down-gear the turbo'ed engine to take advantage of the low-speed torque they make, You will almost automatically get better fuel mileage.
And if you downsize the engine, so that the two of them have similar absolute power output, you will again almost automatically get better fuel mileage.
Check out what Ford is doing with their turbo program. Smaller engines with turbos; can make more torque where the vehicle needs it, similar hp,and make better mpgs when off boost.
With this kindof thinking, you can turbo a 273 to equal a hot street 360 in absolute hp, but make more torque in the lower range. If you down-gear it to take advantage of the turbo-torque, you can make plenty of mpgs .
I know this is not what you asked, but it's what popped into my head.
It has been said, that a draw-through system, can help increase fuel mileage by virtue of the fact that the impeller is smashing the gasoline molecules to bits and homogenizing the mixture, so that all of the molecules get burned. Theoretically this would allow you to run a leaner A/F cuz all the cylinders are burning all of the fuel,all of the time. That would get you better MPGs for sure