If you're considering swwapping the engine why not go with a Thunder Tiger Pro 46. They can be had for about $76.00. Very relieanble and in my opinion every bit as good if not better than an OS. I put a 40 Fx on my son's LT40 and it flies it very well. Only reason I went with that though was I won it at our club meeting. Otherwise it would have been the TT Pro.