[AWSB328iM]

I've noticed the magnet size of an E92 L7 mid is tiny compared to a E90 L7 mid? Why the difference?

[Ali-E90]

I think the doors in the coupes have less space for the magnet compared to sedan.

[Skylinemotorsports]

Any significant difference in the sound between the two

[AWSB328iM]

Originally Posted by Skylinemotorsports

Any significant difference in the sound between the two

But the coupe doors have room for aftermarket speakers with similar size magnets so I don't think that was a limitation. The BMW individual sound system available on the M3 has door mids with bigger magnets too.

[ctuna]

https://www.e90post.com/forums/showthread.php?t=343673

yes extra hard to get speakers to fit in the thin coupe doors see
the above. Its the depth that is the issue.

From the thread
Mounting depth:

Reportedly, e92 & e93 front doors have only about 43 mm mounting depth, measured from the grille side of the speaker adapter.

E90 doors have roughly 50 mm depth.

In order to fit, most speakers need to be mounted with the flange sitting in between the adapter and the OEM grille, see pic below.

They list e90 and e92 fitment notes for each speaker in the thread.