BMW E46 Compact Rear Speaker 5.25 Adapter

This is NOT a plug-and-play solution. 
Modifications to the aftermarket speakers WILL BE REQUIRED! 

Before buying this model, please

1. Make sure your new speakers fit into the speaker adapter ring.
2. Make sure your new speakers fit into the speaker box. PLEASE NOTE THAT the speaker box on the side of the fuel filler neck is smaller than the other side. Coil diameter and installation depth are the main concerns.

Installation

Cut the flanges off of the aftermarket speakers and glue them to the adapter ring, openings on the outer rim are for the flange leftovers. 

Make sure to rotate the speaker relative to the adapter in a way that allows the wiring and connectors to sit within the speaker box without interference with the box when fully assembled. 

For glueing I used SikaFlex 221 but any similar product should work.

I did this since I had a FOUR Audio KC525 5.25 speaker set gathering dust, and the available aftermarket adapters would have only accepted smaller speakers.