The YS 1.10 is a little overkill on the Ultimate also IMHO. I flew mine (Which is the one in the RCU review btw) with a Super Tigre .90 2-stroke. The Super tigre is a pretty weak engine compared to something like a OS .91 2-stroke which I think would be perfect for the Ultimate and still in the overpowered range. Mike designed the Ultimate to fly on any powerfull .60~.90 sized 2-stroke and trust me at 2,8kg dry which is what the Ultimate gets to with a .90 2-stroke it's way overpowered and oodles of fun to fly. My old Ultimate I gave to a very good friend of mine as transporting it without taking it apart was impossible for me and I just hated having to assemble and dissasemble it everytime out, he now uses a Saito 1.25 on it and it's got foamy power. He admits regularly it's a little overpowered and gets tricky to get that sweetspot for the high alpha manuvers. On that same note however I built the Ultimate with good quality epoxy and just glued the mount/sheeting and everything together with a generous amount of glue around the nose area. It will handle the vibrations of the big four strokes just fine if you glue it together properly.