Mvvs 49 is a great engine . you will not be disappointed. Also reckon you use a tuned minipipe to get increase in rpms (~14000 ). As time goes by the engine will run stronger and stronger. Use max nitro at 5% to preserve your engine life.

i am currently using a mvvs40 , 3% nitro , standard silencer on trainer . no deadsticks in 100 flights so far.

now i am breaking in another mvvs45.

a friend is using mvvs 49 in piper cub. using no nitro fuel , quiet silencer, 11*7 prop getting 12500-13000 rpm. flies at half throttle.
another using the same in a seaplane with excellent pulling capabilities.

bobi