Silver Bullet throttle body spacers create turbulence in the air flow at the point just prior entry into the engine increasing horsepower, torque - +5 hp, +2.5 lbs/ft torque - and improving throttle response and fuel efficiency. Silver Bullet throttle body spacers are constructed out of durable T-6061 billet aluminum and using a unique serrated/helix entry to create turbulence at the manifold while eliminating the annoying whistle found in other helix only throttle spacers. This throttle body spacer is 50-state legal (CARB E.O Number D-516-2).
This throttle body spacer fits the following BMWs:

E39 5 series BMW 540i 1997-2003
E60 5 series: BMW 545i 2004-2005
E63 E64 6 series: BMW 645ci, + Convertibles 2004-2005
E65 E66 7 series: BMW 745i, 745li 2002-2005
E53 X5: BMW X5 4.4i 4.6is 2000-2006