My 2015 Toyota Prius V Complete Sound Deadening + Audio System Build

I can't say exactly how much weight the complete sound deadening project added, since I purchased materials gradually as the build progressed and did not keep a running total.
However, I did estimate the combined weight of all the equipment and materials installed in the car, including the audio system and sound deadening. My rough calculation came to around 140 pounds.
For reference, that's less than carrying one extra passenger, which I consider a reasonable trade-off for the improvement in cabin comfort and audio quality.
The sound deadening work had no impact on this. The rubber components were simply old, and the struts were replaced later as part of the suspension maintenance.