no mod at all except the change of controller (plug and... play)
didn't yet test range, but did already 55km, which is two normal days of comuting to work without charging 2*26km plus 3kms... I expect to reach approximately the same range than with 36v, thanks to higher capacity battery, considering more drag at higher speed... (was > 75km at 36v - and even end of battery wasn't reached -~15km remaining-, at 30km/h average).