Every engine requires a steady stream of filtered air to run correctly. Without air, your engine simply won’t run. To put it simply, getting more air into your engine will result in more power. Getting more air into your engine is the entire purpose of a short ram intake. With a high-flow air filter and tubing, airflow to the intake manifold is improved compared to your stock intake system.
Some short ram air intakes include a heat shield to block hot air from within the engine bay from getting in the intake. With a larger and more effective filter and typically a metal or rotomolded tube, restriction is decreased. Unfortunately, many short ram air intakes aren’t as effective as a full cold air intake, however, they are typically cheaper!