too bad you cant rig the BBV to open under boost from the turbo. then you can open up and make the BBV larger.
but like said i think it would be easier to make more power on a turbo alone or a bigger SC. going "twin-charge" as its called isnt as efficient and your adding the extra weight of both systems. also its easier to cool a turbo setup via Air-to-air Intercoolers and larger Air to water. vs trying to squeeze an IC under a SC.
i think the idea is cool and i would love to do it. but besides being different i dont see a reason for it. if your wanting power there are better ways to get it.