ignoring the curves of which id expect the stage 2+ to be better, you have a standard car making 260Hp/313ibft with no hardware upgrades.
most revo stage 2+ cars are making between 260/270hp and 300Ibft on dyno dynamic rollers with intakes, intercoolers, discharge pipes, and HPFP.
so if you can manage that with the stage 1 due to being able to customise, surely the same can happen for a fully modded k03??
Fuel pumps help keep pressure up, there are ways to add fuel to a map without adding pump a pressure
im not saying your wrong, because evidently i am not a subject matter expert, but why did the two biggest names in vag tuning, APR and REVO with their huge R&D depts and budgets take so long to sort it outthe maps so they had no fuel cut and further more take an age to develop the stage 2+ maps