This is BMW parts item 46-31004, described as aFe Throttle Body Spacer for BMW E36 325i/328i/M3, which you can buy online at BimmerWorld at the best price.
BMW E36 E46 M50 M52 M54 325i 328i Intake Manifold Throttle
Intake Manifold+Throttle body For BMW E36 E46 M50 M52 325i 328i+
TOPPERFORMANCE ENGINE COMPONENTS
The Silver Bullet throttle body spacer creates turbulence in the air flow just prior to entry into the engine increasing horsepower, torque and
aFe Throttle Body Spacer - E36 M3
aFe Silver Bullet Throttle Body Spacers BMW M3 (E36) 92-99 L6 3.0
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Silver Bullet throttle body spacers create turbulence in the air flow at the point just prior entry into the engine increasing horsepower, torque and
aFe Silver Bullet Throttle Body Spacers TBS BMW 325i (E46) 01-06 L6-2.
BMW 3-Series E46 (1999-2006) - Fuel & Intake - Intake System - aFe
Eventuri Carbon Intake Plenum - 2006-2013 BMW M3, 325i, 335i, 328i