Think of an engine as a compressor and in it's best day being 100% VE
Realistically it may be from 70-90% because we aren't filling the cylinders 100% all the time.
Think of then adding air pressure to the inlet of the engine, and now it is able to fill the cylinders over 100%
At 2 bar it could be said that we now have "twice as big of an engine" as is actual size and theoretically the VE could approach 200% now.
ps VE only works for WOT.