Well boys.....back to the original question on the post! Will throw in my two cents worth. I have an OS 61FX and its a good engine and simple to tune but not alot of power. I have an Italian Super Tiger 75 and its a great running engine and can only assume the newer versions are at least close. At any rate the ST 75 would run rings around the OS61. Also have a Super Tiger G90 and once broken in, is a great engine with an overload of power. To throw another engine in the mix I would suggest a Tower 75. Friend of mine just bought one and it was an absolute breeze to break-in, tune, and has almost identical power to the G90. Would say that Super Tiger and Tower are good buys for the money.