Any motor can do any wattage you want, its just a matter of how long it can do it.
Generally you go by the height of the magnet/stator, like the mxus 45H is generally typed as mxus 3kw.
The Leaf 35H is typed as Leaf 1500W.
But yeah you could take a very small motor typed as 250W and make it 2000W, easy, motors dont care they will put out until they give ya magic pixie's.
48V 45A (max) and 22A (nom) is pretty good mate, I have a 36V 35A controller that I use 52V on and it gives me plenty of power for the hills.