It was designed for a .60 two stroke glow engine. Back in the day that quickly changed to bigger engines, mine has the YS 1.20 four stroke, that is 20cc. When the Zinoah 20cc came out it was tried but then the DLE came along and it's about a perfect match. Go back on the thread and ask Karol from Jamaica about it. The 30 is just added weight and over kill.
it was also designed for the standard 48 in Oz servos, they work fine but today's digital servos are better but dont waste your money on the high power servos. It's an IMAC design and is crap as a 3D plane. It is however the best Extra of any size I have flown.