Well, sounds like fun. However remember, nothing is free. That turbo must be spun by something.
The exhaust is wasted energy but that is why they use it to push a turbo.
There are people thinking of a hydraulic driven compressor, or course the electric. Both add just as much complexity as exhaust driven though.
Come to think of it, you could use a little collar around the exhaust pipes with water in it, turn it to steam and let the steam push a turbine. I mean steam engines are very efficient anyway.
You could have a resevior, route the steam, drive the turbine, then collect the cooled water and feed it right back to the boiler.
It would be just as complicated as any of the other designs but you would save exhaust restriction. Of course you'd have no boost until your water was boiling but you could meter the amount of water into the pipes slowly.
I mean if you have nothing but time and want a hobby....
