What kind of power do you have with your YS engine? I am very interested in going to the 60 size just for shear size. I love the power I get with my rappy 50, any idea what the power difference will be? Does the Ergo 60 come with a muffler? If it doesn't I may go with OS just because I have a CY muscle pipe I'd put on it and I heared that YS engines don't like pipes.