With my fresh tune, 3rd gear I could carry 90km/h up the worst sections of the eastbound Coq holding EGT's at 1200F pre-turbo.
I imagine 3rd on an A443F would be close to 4th on your manual trans for comparison.
Agreed, as the boost charge cools through the intercooler, its volume is decreased, which leads to the pressure drop you're seeing, assuming you are measuring post-intercooler.