aFe 46-38015 Silver Bullet Throttle Body SpaceraFe 46 38015 Silver Bullet Throttle Body Spacer Serrated Helix Design: The Serrated Helix combination design creates intake turbulence in the combustion chamber. This turbulence breaks up the fuel which creates a more complete combustion cycle increasing horsepower, torque and improving throttle response. The Serrated Helix combination design also reduces intake whistle that occurs with Helix only designs. 6061 T6 Billet Aluminum Construction: All