My flyin' buddy mounts all his engines upright in his UCD, FLIP 3D, Fun World 3D, etc. and loves 'em that way due to easier access, no remote glow, better cooling, no flooding, etc. I mount all mine inverted 'cause it simply looks better, and I just deal with the possible problems. I definately would mount the YS 63 inveted, but that's me. My buddy has a YS .63 in his UCD 46 and mounted it upright, again 'cause it's easier overall.