A throttle body may have a main bore for supplying a fuel and air mixture to an engine. A throttle valve head may be received in the main bore and movable between idle and wide open positions to control fluid flow through the main bore. A main fuel outlet and a boost venturi may open to the main bore and a flow directing feature may alter the velocity and/or direction of fluid flow in the main bore relative to the fuel outlet or boost venturi. The flow directing feature may be carried by the body, the throttle valve head, or the boost venturi.