Hi! John;
The stock muffler of OS GT33 is known as a real muffler among OS gas engine users, it is not like other stock mufflers. When I fly the mod Vanquish, My club mates did not recognize it has gas engine, but two stroke OS 140 RX glow engine which I have on my another plane. The soft mount also helps to reduce the noises from fuselage, and also APC propeller too. I am not a good F3A flier, but just enjoying without any power deficiency. The weight of the Vanquish is now slightly over 5 kg, 5100g due to some reinforcement on the landing gear mount. The weight I think is nothing for the this powerful gas engine. And also The plane is strong enough for all F3A maneuvers.