Steve: I just replaced the isolation mounts on my Legacy RG as they were compressed, tilted and cracked.   The quick drain was also interfering with the nose gear and I suspected that was the reason for some vibration problems I've been having.  I still am getting a good shake after dealing with those issues and have balanced the prop with little effect.   I just read your note on the oil pan and I have to go check.  Did you experience any vibration symptoms or did you just notice the interference or lack of clearance.   I know the io-550 moves forward and left and down a considerable amount in flight from the torque and pull.  The front left isolation mount gets the worst treatment so I think I've got some clearance issues that aren't visible on the ground.  Interested in experience of others.