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Could any of you guys provide me with some noise readings from your cars at 120km/h with a note whether it's on a smooth or coarse bit, what tires you have was done on your car? I know this will depend a lot on the tires etc but it would still be interesting to know. I am getting 73-74db on a coarse stretch and have done the fool boot with Noico (also behind the panels on the side), front doors and B pillars. I am using a free iphone app called Niosh SLM created by National Institute for Occupational Safety and Health. It was found to be the most accurate of app in a test I found on the internet. It has no adds and offers a function to record stretches of noise. I can fully recommend it after using two other rubbish apps so if you could use the same stuff to measure it it would be great. Also has anyone filled the cavity in the pillars C right under the tail gait? It seems entirely empty, at least on top, is very resonant and there are small rubber plugs covering an entry to it. Do I risk much by spraying self expanding foam into it? Would anyone know how the rear lights cabling is laid? I'd think it would be at the same level as the lights. Pic of hole leading to it below

do I need to stick it though to either the tiles or the MLV or can I just place one on top of each other?

I just realised you are in Ireland too. I am based in North County Dublin btw

Goodyear Eagle F1 Asymmetric 5 235/45 R18 98Y XL, MFS - whisper quiet on smooth surface (e.g. motorways in France) but extremely noisy on Irish roads which are made of coarse asphalt ofted with bits of stones. I think going down to size 17 and perhaps a bit narrower tyre would help

Hi Digifish, my question was not in regard to butyl, I know that it's role is to eliminate the vibrations. My question is why people put a decoupler, usually closed cell foam, over the butyl and under the MLV. Why is this layer there and does it need to be stuck to either one, butyl or MLV. Or can I just put it on top and cover with MLV hoping that it's high mass together with the carpet and matts will keep stuff in place.

Thanks Stevie. Unfortunately my tyres are pretty fresh so I am stuck with them for at least a year after which I will try to swap my alloys for a smaller diameter. I already did the boot, the B pillars and the two front doors over the weekend. I put Noico on the resonant panels and in the cavities I stuffed rolled carpet underlay with bags of rolled mineral cotton. The B Pillars are very easy and a very low hanging fruit. For the boot I uncovered the trim up to the rear wheel arches so it was a fair amount of work learning how to take everything out, a lot of surface to cover with butyl and to put it all back. There is really a lot to cover behind the trim, many flat thin metal panels. The doors are on the harder side for a first timer with all the clips and connector. After all this work I do hear a difference, the car isn't annoyingly loud anymore and I can much less hear the noise from the side, like the passing cars. Also conversation is now much easier. On a coarse stretch of an Irish Motorway I register around 73-74 decibel when driving 120km / h. Still too much for my liking. It's also clear that now nearly all the noise is coming from the floor and the wheel arches. Hopefully tomorrow I will have all materials to do the rear wheel arches from the outside and once this is done will be able to report on the improvement in decibels. I also managed to order the MLV and it should be with me in a week or two.

Hi Guys, I am starting to look into sound deadening my Superb and I hoped you'd help me with a few questions what works best or is a good enough solution for sealing the doors? I can see people using butyl matts over the outer skin to close off the interior of the doors. I also saw examples of people using VML. Is there much difference in the result? How is VML held in place with its high mass - tape, glue? when covering the car floor with VML - can I just lay it on top of the decoupler foam and tape the VML pieces together to avoid any gaps, or do I need to stick the VML it to the decoupler? do I really need the decoupler on top of the butyl tiles on the floor at all? I am looking to reduce road noise rather than getting a perfect result for music listening. I was thinking of using foam carpet underlay as the decoupler. It's 5mm thick and was branded as an "acoustic" product when I bought it finally - I live in Ireland and struggle to source VML. After Brexit the UK suppliers just stopped shipping here. Anyone knows where I could get it? thanks!