I usually cruise about 15-17 mph at about 1/2- 3/4 throttle that is were it smooths out for me running 50t. I opened my ports up, and yesterday was the first time I looked and the plug looked very "dry". I have moved the needle to full rich but havent been back out yet but I think the cleaned up ports will justify the additional air/fuel. My top speed has been 23, but I wouldnt do 23 for very long, I am still breaking it in. It is hard to tell what it really sounds like unless you let someone else ride it, but I would gues it sounds like a weedeater on steroids...