I agree. Nissan could have done a better job. It's ridiculous. I was able to quiet mine down quite a bit, probably by 50%. Although I don't like adding weight, I did use Dynamat in the cargo area under and among the spare tire. Then I sprayed the foam inside the areas I could not get to without taking everything apart. Next, I found a real piece of carpet that was very thick online and threw away the paper thing OEM carpet. This helped a lot. It even had a Z emblem right in the middle. Lastly, I pulled all the plastic molding that surrounds the back window and used sound deadening on all sides. I just cut the shapes to fit in-between the lines. After that, it's now very quite. I was surprised on how much noise was coming in from there but on my car, it was clearly and improvement
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