I commented before, but if you are going to block off the turbo-compressors with a butterfly valve, and the turbos also have waste gates to prevent over-boost, why bother with the complexity of the intake tract, for a narrow usage profile?
Why not use ALL of a turbine's potential, by gear-reducing it's high RPMS down to crank-shaft RPMs, and compound the turbine output directly with the crankshaft, and into the drivetrain.
Then use an electric (if it is at all viable to have a big enough electric motor to push the volume of air an engine needs), or a CVT-driven centrifugal supercharger.
The turbine can do what the turbine does best, without the low-RPM blockage of the butterfly valve in that system, nor needing a waste gate to bleed off energy, because it doesn't have to conform to the compressor/intake's limitations.
Tune the separate supercharger to be efficient for the intake parameters of the engine, instead of trying to make the intake and exhaust parameters match, when they don't.
I was much more impressed and enthused about BMW's steam thermal reclamation system, to pull wasted thermal energy out of the engine, and the exhaust, and compound a steam-turbine's output with the crankshaft output to the drivetrain.