My question is about the exaust box that is between the downpipe and middle box on my mk1 driver. I had noticed a rattle in my exhaust and tracked it down to this box, can anyone tell me if this is just a hollow box or if it contains any material that could have come loose? The box looks something like this. I only just had the downpipe replaced a couple of weeks ago so I think they may have dropped something into this box while fitting the downpipe.
