Looking at that BSW link for the E46 as well as what they used to provide for the E53, and just browsing on Crutchfield for what is recommended, why are 5.25" speakers recommended? Is it because a lot of the 5.25" speakers have those 4 mounting "wings" that maybe are large enough to be able to screw the new drivers down in a housing requiring 160mm speakers?

If you look closely on the BSW E53 install video, he had installed a 5.25" speaker in the factory woofer pod which was screwed into some sort of an adapter I think, that he glued in place in the factory pod.

I guess its easier for Crutchfield to recommend smaller speakers that you glue in place than bigger say 165mm speakers that need trimming?

__________________
2018 Ram 2500 6.7L Cummins 68RFE
19k miles -Bright White/Black - Big Horn Sport - Crew Cab Short Bed
2013 X5 35D (CEO's) - Born on 5/17/2013 -
82k miles - Alpine White/Cinnamon Brown/Premium Pkg, Sport Activity/Premium Pkg and Sound/20" Style 214/Running Boards