Hans - I just did a review of the 26- piped and on incowl - the Evolution in cowl muffler is quite good at not reducing power - the Evolution pipe is of course excellent and a bargain. On the Skorepa pipe the sound level drops dramatically and power is consistant with the MVVS Evolution setup
propped on pipe for just under 9000 on the ground - this is a terrific engine for up to 5 kilo full aerobatic setups
for the flop n drop flyers (3D) a bit less weight in the airframe ( 4.5 kilo) is very good -my 9.5 pound Funtana was a rocket .
The best part - I cn't get it to kill in any of the violent flop n drop stuff - it always recovers solidly .