Equally as impressive with the APR intercooler was the external pressure drop (the amount of air pressure behind the intercooler) of only 1.01 psi. This helps to allow airflow to other critical parts of the car such as the radiator and A/C condenser. While the internal pressure drop is important, the external pressure drop is often overlooked. Most other intercoolers commonly cause 1.5 to 2.0 pounds of pressure drop, hindering the radiator from effectively doing its job of cooling the engine.