The loudspeaker in the front passenger door rattles and buzzes at the merest hint of any bass,so I think now is the time to replace the front pair at least.

I want any replacement to fit in the existing space in the door.

Any recommendations?

i would check it is the speaker, think they are prone to rattles under bass,

check the search out

easiest check is to get to the speaker (dont remove it) and push evenly on the cone.

if you feel any resistance or scraping then the speaker has 'blown'

this will show if its blown or just rattle.s

i replaced mine with Rainbow Dreamline SLX components and love them, you will need to amplify them though,

You sure it's not the door card itself? I had to do various things to mine to stop it rattling...

I used to have rattles coming from the stereo. I was all fixed under warranty. It turned out to be the door card, not the speaker. They fixed it by re-arranging the card and the speaker and adding a rubber ring from the mk2 Fabia. No rattles now.

Yep, there was a thread in which this was mentioned not long ago, as my drivers side does this badly.

Although i've not fixed it yet, i dont think it's the speaker, and it is indeed the door card/lining.