nitrous oxide
Nitrous Oxide not a good idea in general. What you can do with it is liquefy it and inject it into the cylinder along with fuel. Whereupon it becomes gaseous and absorbs massive amounts of heat in doing so thus cooling the combustion chamber. Heat engines like a cold input and a hot output because the maximum of work can be got out of it. Work = Heat. Now if you can set fire to it in a petrol/gas mixture (or methanol/gas) it separates into nitrogen and oxygen exothermically i.e. it gives off massive heat and lots of oxygen to sustain and enhance the burning of more fuel. So it helps get a colder input and a hotter output. Lots more work the engine can do. The nitrogen is supposed to guard against pre-ignition but this is a common misunderstanding. However, so good is it at boosting engine performance you need a new engine which does not trouble hot-rodders but does trouble LAMES. It also is not as good at chemistry as it should be and has a habit of forming corrosive by-products. But then the engines don't last long enough for this to be a problem. Lordy another day starts in Paradise... so my advice is, Nitrous Oxide? You must be having a laugh....