Create more airflow to the engine by using a low restriction air filter . A typical stock intake system may have sharper bends in the tubing, which reduces air velocity. Cold air intakes create more horsepower by pulling in denser colder air from an area away from the hot engine. Cold air has more oxygen per volume and has more power per combustion stroke. For every 11 degrees that you lower the intake air temperature, you gain about a 1% HP increase.