No, because there is no restriction bar the exhaust from there, you are interested in the pressure between the exhaust ports in the head and the entry to the turbine wheel, as if there is more pressure there than boost pressure, how can the engine get rid of the waste gasses from the cylinders?
(in very basic terms, and In my interpretation of things
) Don't forget this is a dynamic pressure as well, so even if the engine is doing 7500RPM and the turbo is spinning at 100,000 rpm, the turbine wheel and wastegate can only flow so much gas before reaching choke point, where it cannot physically 'fit' or flow any more gas through the avaliable holes
