The serratedhelix 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 serratedhelix 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 PN 57 - 10013D, 57 - 10013R, 58 - 10007D and 58 - 10007R. See 46 - 34017B for throttle body spacer with factory air intake system.