I have no doubt this would help with the lack of loud enough volume, but I’m not willing to break up the bottom of my phone and void my Apple warranty. It’s really tempting to try just adding a few more holes on the speaker side, but I’ll wait for a more official and less destructive solution.
The two places where the volume is worst is when I get notifications of new text messages and using the speakerphone. I can’t use the speakerphone at all in the car. Thankfully, I’ve got a bluetooth headset for the commutes.