The serrated/helix design creates air turbulence in the intake manifold. This turbulence increases the air pressure in the combustion chamber, resulting in increased performance and improved throttle response. The serrated/helix combination design also reduces intake whistle that occurs with helix-only designs (US PAT 07055513). This Silver Bullet throttle body spacer is precision machined from 6061-T6 billet aluminum for lightweight, high strength, and perfect fit and finish. Its black anodized finish gives a stealthy look. This Silver Bullet throttle body spacer uses all factory mounting locations, making for a hassle-free installation. A supplied gasket provides a perfect seal. This kit also includes a silicone coupling to guarantee perfect fitment and air flow with the factory air intake system. This item will only fit with aFe POWER air intake systems P/N: 57-10013D, 57-10013R, 58-10007D and 58-10007R. See 46-34017B for throttle body spacer with factory air intake system.