That's just great! Do you have any idea on final weight (dry) of your friends plane? I too originally had a Saito 100 in mind as this engine seems to be the best engine (power to weight ratio) for a 60 size plane. Unfortunately there isn't any sold here in HKG, and the OS91 (w/pump) seems to be mediocre in power for an 8 lbs. plane. Last option had to go with the heavier YS110, I suppose the power would overcome the weight. Yes, I too did reinforce the firewall before mounting the YS110. Should be maidened in the coming week or two.