Unfortunately BMW doesn't use door speakers in the E34. I'm not opposed to modifications to get a suitable enclosure at the kickpanel. I am not happy about having to use the kickpanels ....I'd MUCH rather keep the mids / tweeters as close together as possible (including the midbass) ....at least in the kickpanels the PLD's are better. I was hoping to avoid this speaker totally ....but I can't get a 2" or 2.5" to play down to ~80hz. Actually I will most likely be running them 100-200hz @ 18db slope on both ends.
I have also considered the Peerless SLS / SDS 6.5" as well.