Inner door skin done up with Deadpan. I had the stock transparent plastic sheeting removed as that was proving to be contributing to the additional unwanted sound effect.
Rear deck with Wurth material
Rear boot lid with GSI Dampit material
Beneath rear seats all the way to the boot and spare tyre well also with GSI Dampit material
All this is not easy work and takes up a lot of time. I can vouch for that having personally seen with me own eyes the amount of work involved to install all the sound deadening. Lots of cutting and trimming involved. Excellent workmanship as usual from Uncle Yeoh as can be seen from the pixs.
And the downsides? Well apart from the already mentioned high costs, sound deadening also adds mass. A lot of additional unwanted mass! I wouldn't be suprised if I added 20-30kg of mass or more to the Slowtra just by installing said sound deadening. You can really feel the additional mass especially from the front doors. Not good when the N16 is already quite a porker. This is what is preventing me from installing yet another layer of sound deadening to the front doors as I'm still getting the occasional rattling sound during heavy bass. Unfortunately this is a compromise one has to accept for a quieter ride and the opportunity to enjoy his or her ICE more. So who's going to be the first to develop lightweight sound deadening materials?