WARNING: This page is about a different car, the 2004 BMW 760i, 2004 BMW 760Li, 2004 BMW 745i, and 2004 BMW 745Li. However, it is still accessible from the selected car via links, so may be relevant.
Rear seat belt pretensioners are part of seat belt retractor assembly, located on package tray behind rear seat. Removal and installation information is not available.