Nitrous nozzles are a performance part that increases an engine's horsepower and torque by injecting nitrous oxide (N2O) into the intake stream. Nitrous oxide is a compressed liquid that turns into gas when sprayed. This gas is rich in oxygen, and when mixed with fuel, it allows for a more efficient burn, resulting in more power. Nitrous nozzles come in different sizes, with larger nozzles delivering more nitrous oxide and creating a greater power increase. When choosing nitrous nozzles, it is important to consider the engine's size and power goals.