Sonnich,


The tuned silencer is noisier than the regular silencer, but this is mainly because of the higher pitch sound.
If the tuned silencer is cowled, noise will be reduced somewhat.

With the tuned silencer, this engine is capable of spinning an 11.5x6 Bolly prop, at 13,600 RPM.
For this specific model, I would recommend switching to an APC 12x5 prop, which will be spun at nearly the same RPM, but the thrust will be about 15% greater.

From a power POV it will have more than a .70-.72 four-stroke engine.

Cooling is very important for the engine, but the tuned silencer will not be harmed by extra heat (within reason).
So as long some airflow is also available for the mini-pipe, it should be OK. You will have to replace the silicone coupling, every now and then, however.

But the engine, if cowled in, must have sufficient cooling, with a large enough exit behind it and possible with baffles that direct cooling air onto the cylinder and the head. There must be a sufficiently sized, direct flow path for cooling.

About the exhaust deflector; I have had bad experience with it and the normal muffler. It reduced the RPM by 1,000!.
I cannot know what effect it may have on the tuned silencer.