I have the DX7 too with a GY401 gyro. At first I was at 72% gain in the gyro menu, as suggested by the video on the Finless section at helifreak. (it's not Finless, some other guy who made a video specific to the DX7).

So I had the gyro set to 72% in the DX7 menu, which is supposed to equal 32% HH gain for the GY401, but I think there is some misunderstanding about the DX7 value in the gyro menu and the real gain transmitted to the gy401.

Personnally, I had to lower the value in the DX7 menu to about 64 before the little tail wag would disappear. In my understanding, any value over 50 is HH mode, so there is a 2:1 ratio. 64 is 50+14 and 14x2 equals 28 gain for the real value transmitted to the gy401.

So I guess by setting my DX7 gyro menu to 64, I set a real gain value of 28 to my gy401. I dont know if I understand it well, at first I thought I was supposed to set the gain for the gy401 a lot higher than that, but it holds quite well that way and anyway, I get wag if I raise this value, so I'm keeping it this way.

Hope all of this helps a little.

Mat