Just did the full car sound deaderning last week: all 4 doors, tailgate,boot floor, all 4 wheels arches, bonnet, and B pillars. I used Pingjing 2.2mm sound deadener, top with Pingjing 4mm rubber damping liner.
Now the car feels quite and chill.
Bonus shoot, the car is also a little bit lower than before, thanks to the those good 50 kilo sound deadener. Tho the car does feel a little heavier when driving as expected, I don't really mind it.
One small tip: for anyone who has a car with powered tailgate, AVOID use sound deadener on the tailgate. Those sound deadeners just give struts too much pressure due to leverage.
At the beginning I placed sound deadeners on both top and back side of the tailgate. When I tried to close the tailgate, the door was like be smashed. And it could not open by the powered strut itself properly, I had to give it a hand to open. Seems the struts didn't have enough torque to handle the extra weight. Then I remove the sound deadeners on the back side, only leave those sound deadeners on top side there. The power tailgate worked ok then, but still not as smoothly and gently as before when closing.
In the next few days, I kept asking myself: would those sound deadeners make any difference? Maybe yes. But would those sound deadeners make a huge difference? Probably no. Is it worth to taking the potential risk of breaking my struts just for that little changes? Of cause no. Today I finally decided to remove all the sound deadeners on the tailgate. Now the tailgate feels as smoothly as before (of cause it should). I don't find the car be any louder in any circumstances.