Gilles - Your CG Extra 300 will be so nice with the YS120! Will be good to run a 16x8 on her, can it 3D? As for max RPM this is the thing ... YS says something like the YS110 is between 9,000 - 9,500 RPM only. Support forum here says run it at 10,000 RPM ... for me running at 9,750 RPM gives good power and the engine is not that hot ... about 220F only.