I'm not too farmilar with the 2 stroke engines on the 05 3D series. Actually never owned a 2 stroke engine before. Does the gas / oil have to be premixed or are these direct injection? If so at what ratio? How would you rate the reliability of the engines? Thinking of buying 2 of them, but not sure if I should just stick to 4 stroke engines. Seems like the 3D are a lot of fun.