All I know is my own experience and running the diaphragm cover atmospheric pressure hole to inside the fuse made my engine run the same in the air as on the ground, perfect idle, smooth transition with no burble all the way to WOT. Mine DA50r used to go lean inverted and I was always concerned it was going to quit. Now no matter what attitude, what maneuver the engine now runs perfectly. A simple thing to try IMO. Good luck.