You could be right, the doc I read a while ago said they were for the scramble boost settings.
Scramble boost is where the boost increases on a certain event, the Greddy and other controllers have a scramble setting or 'overtaking' setting which you can activate with an external switch mounted somewhere like the steering wheel.
Handy for those "Oh bugger theres something coming the other way when overtaking" moments.
AFAIK ours allows you to increase or decrease the boost (ratio) when the limiter is reached.
The gain is used to control how quickly the boost increase by fiddling with the wastegate.
If your right though, and I hope you are then I'll be quite happy