I see several comments about right and downthrust not being very pertinent in the above ocmments. I tend to dissagree strongly. On all my planes, minor changes in thrustline have often greatly improved flying characteristics. On Bipes and high wing planes, it is very much a part of the trimming out process to get good flying characteristics. I like a model to go where you point it and not change directions with change in throttle settings. This will not happen unless the thrustline is properly tuned to the aircraft in question. It is almost as important as the relative incidence settings between wing(s) and stab.