AFE 08-10 Ford F-250/ F-350 6.4L Crew Cab/ Short Bed Large Capacity Fuel TankSerrated Helix Design: 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). 6061 T6 Billet Aluminum Construction: This Silver Bullet throttle body spacer is precision machined