The aFe Silver Bullet Throttle Body Spacer (part 46-31002) is a billet aluminum spacer that mounts between the factory throttle body and intake manifold on the BMW N54 twin-turbo inline-six. The manufacturer specifies that the spacers are constructed from 6061-T6 billet aluminum and precision machined. It is listed for the 335i (E90/92/93), 135i (E82/E88), and 535i (E60/61) with the L6 3.0L N54 engine, so it suits owners who want a machined, bolt-on airflow change for far less than an intake swap.
The main reason to pick this model over a cheaper helix-only spacer is its serrated/helix entry. The manufacturer says the serrated/helix combination reduces the intake whistle that helix-only designs produce. Its stated aim is to speed up incoming air and sharpen throttle response, not to deliver a fixed power number. Owners on user forums are skeptical: one N54 owner said they had not seen proof that spacers do anything on these engines, and others questioned the mixing benefit on a direct-injection motor. Treat it as a low-cost tweak with unconfirmed gains rather than a power package. Searches for an N54 throttle body spacer, a 335i billet spacer, or an E82 135i intake mod will often lead to this exact part number.
The manufacturer lists the 335i (E90/92/93) for 2007–2010 and the 135i (E82/E88) and 535i (E60/61) for 2008–2010 with the L6 3.0L N54. Confirm your chassis code and model year against that list before ordering.
The manufacturer says its serrated/helix design is meant to cut the whistle common to helix-only spacers. One owner on a user forum said the serrated edges decrease the whistle at idle and cruising speeds.
The manufacturer emphasizes that the spacer increases air speed, improving performance and throttle response, but a confirmed horsepower or torque figure for this part was not found. Owners on user forums doubt that gains are meaningful on the N54.
This is a bolt-on job rather than a major teardown. Owners on user forums note that the four throttle body bolts are reachable once the intake tube is out of the way, and the throttle body can be swung clear of the manifold. Expect to need 10mm sockets and a torque wrench. One owner noted that the spacer seats with a distinct pop when fully pressed in, and another found the gasket orientation unclear, so follow the included instructions closely. The torque value for this application was not confirmed in the research, so use the manufacturer's sheet for the final bolt tightening.
