Who sends it? Corporate VW or dealership where vehicle was purchased?
VWoA sends the letters out. If you've moved since your purchase, you may not get it. You can check
https://www.nhtsa.gov/recalls to see if your VIN is included in the campaign.
I just got mine back (airbox mods only) and took a short drive (have to start dinner) and here's the major things I noticed.
Start/Stop is smoother, it used to clunk when stopping and vibrates when starting. Most of that is gone now.
Accel is smoother in D but still laggy (I mostly drive in S)
Maybe related, maybe because adapations are reset? Dunno, I can only speculate.
I've picked up some DSG farts at a much lower RPM, previously I'd only get them over 5k. Got a few small farts around 4200rpm now and there is a bit more burble. I doubt it's related, but I got more farts on this drive home than in the months since I changed to the TCR suitcase.
Exhaust doesn't sound the same, it's lower in tone and seems to have more of a growl.