Stacked units are tough with noise complains all the time.

It is honestly a grind to find deals right now but they are out there.

No joke, they'll just let you buy super cheap houses other places if you don't have them where you live ;) In all seriousness though coming from a high COL area (Seattle) My advice is that you either need to GRIND and make deals- and then you're going to hit 1% rule most likely, not 2%.

If you do add them, would there be noise problems between units?

The contractors said they could hear noise inside but did not open the door on multiple days. 

How often do college students complain about the noise from other college students in student housing properties anyway?

Before that, A & B were fighting over the parking, and B told A to "F" off and refused to speak to them, B purposely made loud noises to disturb A, childish behavior like that.  

If someone rents the bottom part of an up-down duplex, they have to expect a certain amount of noise.  

I have told them we can support less noise in whatever way we can (door closer etc) but they need to figure out between them the noise issue.

No need to grind it into the dust