@Rallyfinnen I think you might be right about the timing angle, one of my repeated measurements came out as cca 185°. I could have used the wrong technique when measuring; Shined a flashlight through spark plug hole and basically measured between the times I can see any light coming through, used the magnet rotor to set marks. A solid, definite number would be useful; my machine has a 3MB00 cylinder and a standard thin gasket, it is not marked with "P" and has never been bored or ported.
As for the temperature, I didn't get reliable numbers with a multimeter probe at the flange with the exhaust off, so I opted for calculating it via BMEP which turned out right around 7.10
The temperature would be lower at the middle of the pipe and even lower at the convergent cone, the highest temp is supposed to be right at the exit of the cylinder and if I'm not wrong, that's the part that creates the pressure wave.