Change max deflection angle tricopter servo

Where can I change the maximum deflection angle for a tricopter servo.

I can multiply _rc_yaw.radio_out; in AP_MotorsTri.cpp:

But it doesn’t seem to be the most elegant way. Is the deflection angle determined somewhere in the code?

Multiplying isn’t a good idea because it also increases the minimum value. But does anybody have an idea? My servo’s are capable of much more and I really need it. It must be limited somewhere in the software but I don’t know where.