Originally Posted by VP Electricity
...Whatever adapter is used needs to both mount the speaker to the BMW mounting holes and act as a spacing gasket against the back of the door panel....
I'm really happy that this thread started and thanks for that. I thought I'm sharing some of the picture I took of my partly done install (6ch BASE system with no amp -> upgrade with MS-8 + amp(s)). Will start my own thread sometime later as the upgrade didn't really meet with my expectation yet in terms of SQ improvement and wanna ask some advice.
Front speaker adapter made from MDF:
Base stereo front speaker versus Polk Audio db501:
Speaker into spacer:
Height diff OEM vs Polk: