On my Mi2, if anything the call volume is too high. Everyone in the room hears the conversation as well as I do unless I put it on like 40% or something.
I'm using WIUI ROM though, not stock one, that may have influence.
I can't really test it at the moment since I don't have any USB data cable, just fast charging ones with the data pins cut out.
I hope the rest of the people are enjoying this though :p
flash gapps from the recovery to the system partition where you installed the ROM.
For that ROM these are the correct ones:
http://goo.im/gapps/gapps-jb-20130812-signed.zip