The handbook confirms it.
In fact, according to TAGTT 151/152, any Bf 109 G could increase VNE to 850 km/h at 1km and 800 km/h at 3 km if it had the following requisites:
1) Enlarged tail fin & rudder
2) Horizontal stabilizer trim range reduced from +2º to +1º 10'
3) Elevator fitted with enlarged tabs (350 mm)
4) Reinforced ailerons (bearing pins with a diameter of 8 mm)