If you are going to return the .46, do yourself the favor and get a 4 stroke! By the time you pay for a 61 and get a pitts muffler for it, you would end up spending the same amount you would for a Magnum .70 and the .61 will never sound the same! Usually when companies recommend a range of engines, the lower number is the minimun amount of power required to fly that model while the highest number is usually perfect for sport flying. Always buy one in the middle to the upper range of the scale.