Well you aren't going to get 40 with 15/38 and stock 2nd gear with a 9XL unless you go to a 6S pack, which I would definitely not run with your MM. If you need it that fast then you need to run something like an 18/36 or 18/34, and probably use the wide ratio gear set. I think you should put the 2 speed back on, helps keeps temps low, easier on clutch, and will give you wheelies, plus, you should reach the top speed faster. Now, after saying that, I think a 6000 or 8000 4S pack would be best for you. Lotsa runtime and the weight is nor a big penalty for bashing. Also, check out BrianG's calculator, it'll really help you with gearing and motor choices. Good Luck
