Billet Intake Plenums upgrade improve airflow and provide much more resistance to blow out from high boost levels. These new plenums cure plenum leaks from the stock stamps intake plenums. Leaking 7.3 intake plenums cause power loss because not all the boost is going into the motor. This causes poor fuel mileage and power loss. If upgrading the motor with injectors and turbo these plenums are most important as an upgrade because the weaker stamped OEM plenums are even more likely to leak or fail. IDP plenums- these will not crush and can withstand high amounts of boost. These intakes are thicker and have better clamping force to the engine. Please be sure to select which heads you have from the options. The early heads had 4 bolt hole sets and the 95 and up heads had 5 bolt sets per head.