Both D9's has standard flexi pipes.
Not cut, so the pipe ends are standard. Important for good sound.
The black yellow spinner D9 has 33 flights. (ESM)
The spiral spinner D9 perhaps 20. (Sist)
Flights last perhaps 10 minutes?
The cylinders are tightly baffled, yes.
And again;
Just remember to put 20ml oil into the crankcase before the very first start. Extremely important.
There is no lube there, then. They come completely dry.
(Common for most RC 4 strokes, really)
L-needle; 6.5 ( !!)
H-needle; 1.5
I love this engine. But of course, if something happens, that will change. But by then I have had lots of joy with it already, and don't worry about it.
Haven't adjusted anything after the first flights, and it starts and runs fine every time.