Hi!
If you change the rear ball bearing to a WIB C4 bearing, removed the head shim, Used a Nova Rossi 4 or 4A glow plug, you could expect around 14000-15000 rpm using the MVVS 3248 mini pipe.

The standard MVVS .40 engine turns a 10x6 APC at around 13200-13600 rpm on FAI (80/20) fuel.
Best 10x6 prop is either a RAM or Graupner "Cam-prop", not an APC!