Jeff, the OS91 is way too much power and way to heavy for that plane. The regular OS 70 4-stroke is already very nose heavy on the plane. There is a lightweight version of the OS 70 4-stroke that is the absolute maximum as far as weight is concerned. My 11 year old son has 2 Excelleron 50s. One is powered by an OS55AX and is great. It is currently his practice plane. The other has a YS63S on it and is awesome. He is not flying it right now as it is his contest plane. Both are a bit nose heavy with the YS being a bit more so. Your 91 Surpass will make your plane a bit more difficult to fly and hotter to land. I strongly suggest you trade it for either a YS63S, an OS 70FL, an OS 55AX or an OS 50SX in that order. Just my 2 cents worth.


Jayjay