SRC Speech RX Volume
5_lvl : 88
Menu -> Key Input
Change to any number greater than 88 (Max:100)
Press back to save.
It will reset after a reboot so be sure to run through it again if you wish to increase the volume level again. There isn’t enough testing done or reports at this time to tell if moving the volume past 88 will damage or blow out your speaker. So as usual if this mod blows out your speaker you are using at your own risk.