Fuel: 0% nitro, 12,5% castor and 12,5% AeroSynth2,
APC 8/4 prop.
Weather 11 degrees Celsius, rainy, see level.
With stock muffler:
12300 RPM, 3700 idle.
With old pipe from a Carlsson 1/8 on-road car from approx 1982 (not a tuned pipe, see picture). The length didn't make any different in the RPM's (tried 8 to 16 centimeters from the engine to the start of the pipe).
Oh my, what a crispy sound
13300 RPM, 3700 idle.