I've been doing a fair bit of soundproofing but can't get to the rear arches from the inside. I've followed the service manual but it starts getting hairy as soon as it gets to the plastic part at the top behind the rear seats where the seat release handle is. Has anyone done this before who can give me a hint? I can't believe I have to remove the rear seat backs etc to get to this..

 

I would personally suspect a screw under the D-pillar cover.

 

 - Bret

Search for tow bar. There's a pdf in one of them (sorry can't find it myself just now) that shows removal of the rear parts you want access too, at least one side anyway.   

I've got the service workshop manual (body) pdf but it looks like you need to rip out so much to get to it.

 

Remove seat bench, side airbag, wheel house trim panel, trim panel of panel c, seat back rest etc etc etc

 

Looking for a shortcut!