Making a Nitrous oxide kit is not as hard as it seems. Nitrous oxide is an oxidising agent which provide more oxygen to petrol than air and can give more power in engines. The aim of a nitrous oxide kit is to inject nitrous oxide in to the combustion chamber.
Making the NOS kit:
- Carbon Dioxide fire extinguisher
(only carbon dioxide alloy cylinders, other will explode)
- Solenoid (nitrous and fuel)
- Steel Braided hose lines
- Brass Valve, 2.5 - 4mm internal bore
(compatible with all internal combustion engines including motorcycles)
Made by burgerman

Expty the co2 fire extinguisher, remove the original valve and fix a 1/8 bsb thread valve (internal bore from 2.5mm-4mm, to wide will loose velocity, too narrow will give excess resistance).
Add a siphon tube to the valve to draw out liquid nitrous oxide. Fill the cylinder with nitrous oxide at about 2000-3000 psi
more details on http://www.diy-nitrous.fsnet.co.uk/motorcycle-nitrous-injection-system.htm
http://www.diy-nitrous.fsnet.co.uk/car-nitrous-system.htm