My impression is that the deep trunk acts as a resonance chamber for road noise so I took a look to see if there might be an easy fix. There are some noise dampening pieces on broad metal surfaces under the trunk carpet and one big sponge under the floor of the trunk. Here are pics looking under the lifted trunk carpet (it is continuous forward under the seats and I did not want to remove them for this project). The transverse piece marked by the yellow arrow has a thick (~2”) white foam covering it which extends foreword over the motor but the portion covering the top of this bar is thin compared to the rest. [ I covered the exposed metal starting from the top of the bar and going aft with Noico dampening material. I did not remove the side carpets—which at least on the left would expose more bare metal but the amplifier is on the right—or expose the wheel wells for modification. According to my free iPhone app interior noise dropped about 5dB and my impression is that the car is much less “boomy” and seems noticeably quieter. A pro install treating more areas could accomplish even more but I am satisfied with this improvement, now the front wind noise is the major offender. http://a.co/9rxcgvY I had bought this material to apply to my X but found that car had quite a bit of insulating material in the trunk area already.