The aFe Silver Bullet throttle body spacer (part 46-31011) is a billet aluminum spacer that mounts between the throttle body and the intake manifold on the N52 3.0L inline-six in the 2007-2013 BMW 328i (E90/E91/E92/E93). Its serrated helix entry is meant to churn incoming air just before it reaches the engine, which aFe says improves air speed, throttle response, and fuel efficiency. The serrated profile is the main reason to pay more than for a basic spacer: helix-only designs are known for an intake whistle, and this one is aimed at quieting that while keeping the airflow benefit.
This N52 throttle body spacer is designed for buyers who want a machined, bolt-on upgrade rather than a stock-look plastic or unmachined part. It is 6061-T6 billet aluminum with a black anodized finish. Per the listing data, it is made in the USA and includes machined screws and gaskets for a secure, factory-style mount. It is listed for use with several aFe intakes (including 51/54-81012-B/C and 54-13053D/R), so confirm your intake before ordering. Check CARB eligibility before buying if you live in California, since listing data on CARB status varies. Search terms: N52 throttle body spacer, E90 328i intake spacer, billet throttle body spacer 46-31011.
This is a bolt-on job at the intake side of the engine. Expect to remove the intake tube to reach the throttle body, separate the throttle body from the manifold, fit the spacer and included gaskets, then reinstall the throttle body and intake tube with the supplied screws. Use a torque wrench and tighten evenly, and check for vacuum leaks and fault codes after the first drive. Confirm the torque values with the manufacturer's instructions before tightening.
