I have a naza m lite and a flamewheel 450.
I like flying in GPS ATTI and ATTI mode.
But i like to fly faster.
I this possible by increasing the pitch gain?
It's an open space and i like to fly fast with my quad.
If you increase Attitude gain the sticks will react faster and copter will come back to self level faster as well.
This is about all you can do I think to increase responsiveness on the flight controller
A 4S battery would increase your top speed by increasing the top prop RPM.