Hey all, I am completely new here, so go easy on me.

I am the proud owner of a 2003 Boxster S in the UK. It has just come back from a rather expensive service but now I have new brakes, tyres, seals and ignition coils.

However, before it went in I had asked the mechanics to investigate a knocking noise, they road tested it with me and it was clear. When I collected the car the knocking was still present. They have told me it is nothing mechanical. All bushes, wish bones, suspension elements are all sound.

So now I am lost! So I thought I would appeal and see if anyone has had the same problem as me and what the solution was.

Here are the symptoms:
It is coming from the nearside (left side) rear of the car.
It only happens when the engine is at temp.
It only happens over bumps.
it only happens when coasting - so it doesn't happen when I am accelerating or braking.
The noise is kind of a hollow clonking noise that only happen when i am going over slightly bumpy roads.

To me it seemed like engine mounts or something but Porsche say no.

Any help?