Gross increase with STOL?

[B2C2]

I have a Robertson equipped 1969 T337D with the original STC paperwork. the differences in GW increase are for NA vs Turbo models.

NA GW is 4630
Turbo GW is 4700

This is true for all models A-G

for my aircraft all weight above 4500 must be carried as fuel, and max landing weight is 4465.

I can scan and post the full STC if you would like.

Ben