The only reason I say beef up the firewall is that usually the engine of choice for this Plane has been a 91-100 4 stroke, and the occasional 120 4 stroke. I have not read where to many have used the YS 110. I would compare the ys 110 more towards the 1.20 and maybe even a bit more powered. I always remember VectorFlight suggesting that you should reinforce the firewall if you were going to use a 1.20 size four stroke. Since the YS engines are well known to be extremely powerfull, it might not be a bad idea to add a little reinforcement just to be safe. Don't want that high dollar YS engine falling off the front in flight!