RobertC, you've flown your so I will ask your opinion. I'm picking mine up at the LHS next week and I have an OS 120 ( non - pumped ) 4 - stroke to put in it and even a nice incowl elbow & flex pipe to shoot the muffler out the bottom with an inverted engine. But I have also been thinking about a YS 110 ( yes I can get one ). I know I'll save 5 - 6 ozs. but not sure about the extra power. The question is - in your opinion is it worth while spending the extra $$'s or will the 120 be enough. I get about 9200 on an APC 15 - 8.