i believe that if the two turbos going into the intercooler are both producing 14.7psi each
They are only producing this off half the air required to run through 6 cylinders, hence having two turbos, each run off 3 cyl each
By having "two lots" of 14.7psi of boost, you are not multiplying it together and gaining 29.4psi
You are just feeding two units of pressurised air into the plenum,
i.e. PSI = pounds square inch yeah??
so if you had 1 inch cubed of 10psi air, and add another inch of 10psi air, you are not getting 20psi
because you now have 2 cubed inches of air, both at 10psi each
make sense??