The popcorn exists, most likely because the car is so insulated that without it I wouldn't hear much of anything. The popcorn comes through all the sound deadening, the raw exhaust doesn't.
I'd actually like more exhaust sound (even that is fake engine noise above like 3k rpm) to the popcorn but I'd assume sound regulations plus the sound deadening had them go this route.
It is, honestly, fairly obnoxious, when you have the exhaust in the highest setting, especially if you have the rear seats folded down. I think its hysterical but it is pretty asinine at times, I've had it just repeatedly doing popcorn for over 5 seconds and its so ridiculous.
In the lowest engine sound setting it pretty much doesn't exist. If you touch the PTM modes (the knob on the steering wheel) you will bring it back. If you go to sport mode, you will bring it back. You will have to setup your MyMode to have engine sound in the lowest setting, which will make your exhaust whisper quiet, but also eliminate the popcorn. If you do get popcorn on some higher rpm overrun, it will be very minimal.
Leaving your exhaust in the lowest setting probably won't 100% eliminate the popcorn but it will in 90% of your driving, you will probably have to live with the other 10%, if it does happen it may only be for 1-2 seconds.
If this is the only reason for not wanting the car, I think its completely tolerable for you with the exhaust in the quietest setting. There's always something we don't like about our cars that we deal with because the other 95% of the package is awesome. Nobody is ever 100% satisfied, I think you will be fine.
In the name of science I will try to test out Tour mode and MyMode with exhaust in the lowest setting and see if I can get any popcorn in normal driving and at higher speed overrun today and report back, I have a 2-2.5 hour drive to do.