458 Clunking noise in the RHS drivers door

I have to buckle the passenger seat belt, or I hear it bang against the carbon fiber passenger seat.

 

I have to do this as well

 

Hi, interested as well.
Same car, a "clunk" low behind me (around down my back) but it happens to me sometimes when I turn right, never over bumps. Not very often.
I am positive that, in my case at least, it is not the belt buckle: definitely the noise is still there even with the belt buckled, plus it comes from somewhere else.
Possibly from the foldable top storage (I can't recall if the noise is still there with the roof closed, sure it is there with the roof open, I think this is an important point to sort out), or the engine bay.
In my case 99% it is not located in the door, so I would recommend to take some more time before dismantling it; of course it may be a different issue.
Same question as Nigel: ideas?

 

Ops... sorry I now realize you are mentioning the "RHS driver's door" whereas mine is a LHS drive, so, once more, it may be a completely different issue...
I confirm mine clunks behind the LHS seat (i.e. driver's seat on mine) on some right corners.
Apologise for misreading.