Those are raw data so there might be mistake here and also i wont give a explaination before i try everything out.
Killigorn NO TAT
Killigorn MPR 150 before training with Beleg +8 121,493 PR 5,201 (+5051)
Killigorn MPR 155 minor training with Beleg +8 121,493 PR 5,206 (+5051)
Kiligorn Power Rating: 4,238 with MSG +16 93,114 (+4083)
Kiligorn Power Rating: 8,118 with MSG and beleg (+7963)
Kiligorn Power Rating: 46,828 with big tat (+46673)
Kiligorn Power Rating: 49,132 with big tat beleg (+2304)
Kiligorn Power Rating: 50,879 with big tat MSG BELEG (+4051)
F-AMg Power Rating: 16,611 no tat
F-AMg Power Rating: 16,734 with tat small tat (+123)
F-AMg Power Rating: 21,662 with beleg no tat (+5051)
F-AMg Power Rating: 24,574 with beleg and MSG (+7963)
F-AMg Power Rating: 21,701 with beleg and small tat (+5090)
F-AMg Power Rating: 63,284 with big tat (+46 673)
F-AMg Power Rating: 65,588 with big tat and beleg (+2304)
Conclusion IPR increase dont change with MPR so the NW=PR is linear on a base per 1 item but they wont scale linear if you stack item.
NW decrease TATPR in sync with TAT size and it a non linear curve as teh beleg alone took 39 point (close to 25%) off the small tat but the Beleg took only 2747.
IN % 120KNW on a 170 level tat was 39 or 25%
IN % 120KNW on a 115 720 level tat was 2747 or 2.37% (the ratio is about 10:1 bettween the big tat while in % is only 0.146)