i want to get an engine kit for my bicycle. I want a fast one and want to be able to put nitrous on it cuz i know that they sell kits with nitrous. I want to be able to go at least 30mph. and i want to know if they are universal i have a mountain bike i think its 26" or 24". does size have to matter. I also want to know if u need like a license or something to drive in the street