randomly when I'm driving around sometimes the car starts doing this noise. I was in process of reversing when I took the video but revved it a little more so you could actually hear what was happening. The exhaust note becomes deeper and a burning smell appears. What else I have noticed is that when you have the clutch to the floor it happens more when it occurs. Also the Rev counter drops to below 900rpm after you give it a sharp rev then bounces back up to around 1/1100rpm then settles...

It's becoming a bit of a worry now.

Video here : https://www.facebook.com/andrewfinnon/videos/943504265713640/

No video upload AF probably why your not getting a great response upload it and someone should be able to help

It sounds like a DPF regeneration and nothing to worry about. :)

It mentions this behaviour in the user manual. I know that it comes from the particulate filter but what is it actually doing ?

It's burning particulate matter that the DPF traps & turning it into ash / CO2

That noise as it comes down the rev range does not sound good at all, that is unlikely to be due to it doing a DPF regneration. It sounds horrid. Can you get someone else to video it with the bonnet open while you rev it, that does not sound right at all.

Sure that video wasn't working earlier! :s

The noise on run down is turbo chatter. Probably being caused by the backpressure from the DPF.