Treynor is right, you are wrong.
PV=nRT helps tell us the density of the air in the manifold. There is no MAGIC associated with bigger turbos flowing more. You are thinking of bigger turbos being more efficient at compressing the air. That is, less heat is added when the air is compressed. The amount of air flow is governed by the manifold and head design. It will flow the same volume of air at the same manifold pressure, no matter what device compressed it. 6psi from a tiny turbo will put the same volume of air in an engine as 6psi from a huge turbo. Now chances are the tiny turbo will produce hotter air meaning the MASS is less.
If you read my response properly, and know the actual physics behind this, you should understand Ben's response.
PV=nRT
I am giving the intercooler the benefit of the doubt and saying T is the same at 6psi as at atmo. R is a constant. V is fixed. P is 1.4 times atmo at 6psi. Therefore n (number of moles of air) is AT BEST (ie 100% intercooler efficiency), 1.4 times that at atmo. So the best the engine could do at 6psi is approx 1.4 times at atmo. Well sized turbos operating at or above 80% efficiency, with very good intercoolers, will come *close* to this, but not achieve it. There are a few cases where you can use some tricks to very very slightly exceed this, but they are mostly related to exploiting deficiencies in the engine at atmo which change its volumetric efficiency at boost.
It *IS* possible to put an upper bound on the mass of air entering the cylinders, based solely on the density ratio. It does not matter what is producing this compressed air. If you don't understand this, you don't understand the means by which an engine aspirates compressed air, and the workings of the device producing it.
Your second post is wrong too. You are just explaining volumetric efficiency of the engine, which you are planning on changing from, say 85% for atmo, to 100% for FI. It doesn't work like that, either.