You would have a huge boost leak like that. The air produced by the turbos has to enter the same place above the carbs. The turbo air entering the engine has to be totally sealed. If not you got a boost leak. So all air into the engine would need to come from the turbo outlets that enter at the back of the manifold above the carbs.
So with the way you are explaining once you cracked the butterflies you would instantly have a boost leak. Plus the blow off valves are constantly pulling vacuum keeping them open bleeding off the boost the turbos are creating the way he has it plumbed.
Very complicated funky set up. All for show and no go.
