The idea on steering is as follows:

On a normal set up radio the steering is linear. That is you get equal steering response across the whole range of movement of the steering wheel.

For Minis, you need to reduce the steering rate to a negative exponential. That is , the movement of the steering is reduced for small movement either side of straight ahead. The steering rate increases as you turn more. This eliminates the twitchy feel around no steering input (straight ahead)

On KO radios it is called steering curve. I dont know on Futaba