Flight angle control

i want to decrease the angle when the F450 fly in position and mission mode.
And when i change the param MPC_MAN_TILT_MAX and MPC_TILT_MAX to 20deg.
The mission mode angle be better like the down picture,but the rate go bad:

The position mode ange can’t stop when the target angle be 20deg.like below:

so do i should change the pid value of rate in attitude? or try to change the value "THR_MDL_FAC ",to make the thrust and pwm be a x^2 relationship.

Maybe i find the MPC_DEC_HOR_LOW can do somework.

It seems that your Pitch Angle Rate controller is badly tuned.
If you send me the log I can help.