I'm flying a Trex 450 in a Hughes 500E fuse. When I add power quickly the nose yaws left just past 90degrees due to the torque. When I drop the throttle the nose will yaw right less than 90degrees. I'm running a GY401 w/S3154 and a DX7. I was told that I should run a 5.1v step down for this servo when using the GY401 so I installed a step down and getting the same results. Did I already blow the servo or is there something else that I need to do?

try turning the gain on the gyro up a bit.

I have it at 87% now. Knowing that, do you think I should turn it up more?

How far out on the servo horn is the ball link on the rudder servo?

I'm not sure in mm but I have it close to the hub. Additional info.....now I have the gain all the way maximum to 150%. No tail wag and it still yaws but as pronounced. It seems that it gets worse as you get closer to maximum flying time.

Move it out two holes and set your gain to 100. You are in HH right?

Yes it is in HH. I will try making the changes. Thanks