Four common causes.
Cause 1: The smoke limiter is still capping you
Symptom: car pulls well at part load but flattens at high RPM/load. Fix: check smoke limit map against your new injection targets.
Cause 2: Rail pressure deviation under load
Symptom: inconsistent torque, sometimes a P0191. Fix: check actual rail pressure on a datalogger while driving.
Cause 3: Torque limiter still at stock level
Symptom: good power then sudden pullback. Fix: raise torque limiter maps proportionally.
Cause 4: The original file was already modified
Fix: always read the current ECU content, compare to stock before starting.
The +21% result comes from rail, SOI, pre-injection, and smoke limit working together. We work through exactly this combination in Diesel Practice, Chapter 3.