Glf brakes
Research suggests that the MOD is the old mod ie the restrictor valve in the hyd line.
This mod never worked for me, or any other G550 guy I know.
Glf themselves say it is not worth doing.
So unless this is a mod that my man in Glf is unaware of, just use the one foot technique. Use alternate feet whenever you see a significant rise in your blood pressure or aircraft brake temperatures.
glfflyer