R&D Power Core Intake Manfiold Sleeve (intake manifold upgrade) The R&D Power Core Intake Manifold Sleeve Kit was developed to increase airflow into and through the intake system by relieving restriction. The R&D Intake Manifold Sleeve replaces the OEM intake ribbon producing a 40 CFM increase in air flow. The R&D billet sleeve mounts into the intake manifold and extends up into the throttle body creating a superior Venturi effect. The R&D Intake Kit will add low end and mid range throttle response