the interesting this is,

If a turbo is producing more boost than the engine can consume - the boost pressure would rise

There is more air available at the inlet manifold than can be consumed - so the boost gauge would read more pressure - thats it.

I wonder here if the actual term "Surge" with relation to a compressor map is the problem - surge could perhaps means something else as well - its the surge line on the compressor map i'm intereted in