I decided to fly Imac this year for the first time . iahve been flying for some years now off and on but would like a challenge and not just burn fuel

the two planes i am building right now is a greatplanes matt chapman cap580 and a greatplanes Yak 25% . the yak will have a DA50 .the cap580 i am between a YS63s or a OS61dx .

Question ... which engine will be better for the cap ..?..i use 15% coolpower for my planes and 305 for heli.....i fi go with the YS do i have to use 20% . Also in the 20 years i have been in this hobby i have never owned a 4 stroke engine .

Question which plane would be better to use at the imac meets .....?

thanks