I am Gary from New Zealand.
We have just bought a 2014 Silver NV200 7 seater vanette that is fully trimmed inside and looks luxurious, a bit like the inside of a Toyota Hiace Super GL. It is imported from Japan with 64000km on the clock and seems to be immaculate. However, it has high road noise with some resonant vibrations in the panelling, so we will remove the panelling and install self-adhesive acoustic padding to the inside body surfaces. Also under the engine bonnet and any other bare metal surfaces we can access. I don't think the roof needs doing because it sounds nicely dead when knocked. Most of the side panelling sounds rather drummy when knocked. I would be pleased to hear any comments or advice.
All the best