today i retrieved my car after the installation of the "stage 2 interior sound kit" on my 2.0 roadster (i had previously had the "stage 1 interior sound kit" installed.)
i also had the "cabin area HVAC tube upgrade installed.
first thing to note is that the stage 2 interior sound kit was over $3K (~$1600 for the parts and $1400 for the labor)
the HVAC upgrade was $100 for the part and $175 installation.
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the results of the stage 2 sound kit are both subtle and appreciated. i think the main changes i noticed in a couple of hours of city and highway driving was a reduction in ambient noise (especially engine whine) and also the door closing sounds feels/sounds very different -- more like a mercedes than a kit car. i'll be curious to see if conversation with a passenger is less effortful.
i did not notice much of a reduction in road noise (from bumps and such.)
the service manager at tesla menlo park mentioned that someone at tesla had measured 5dB-10dB overall noise reduction.
overall, i am (as someone minorly obsessed with making my roadster quieter) pleased to have had it installed but it admittedly does not make the same type of dramatic difference that the "stage 1 kit" made when i had that installed or even the adjustable suspension (set on softest setting) + tires in comfort mode.
given the moderate SF weather, i did not test the HVAC upgrade but it seemed like a nice to have for those few chilly night drives.