I've recently installed a pixhawk running Plane 3.4 into a 2015 Skywalker 1830. The plane flies pretty nicely in Manual and FBWA modes but there seems to be an imbalance in the aggressiveness of left and right turns in AUTO mode. When turning left, the plane seems to under steer and take a long time to get back on track. The opposite happens when turning right however, with the aircraft over steering a lot, which often results in tip stalling.
If one or the the other action happened for both directions I would usually be able to tune it out, but if I tune for one circumstance it makes the other worse in this case.
The plane is balanced about the longitudinal axis, and there doesn't seem to be any uneven twisting in the wings. The propeller is spinning in a clockwise direction when viewing it from the aft of the plane, which I'd assume would aid the aircraft to turn left with torque roll, if there is enough torque roll to make a noticeable difference.
Has anybody else experienced a similar issue? Am I missing something obvious? Any help would be really appreciated!
I've attached param and tlog files of the plane doing a survey grid. Here is a dropbox link to the .bin file.