Volume Boost is an extension for GNOME Shell that allows you to set the volume up to 150% from the volume control slider in the status bar without the need to go to sound settings.

Copy these files in your folder ~/.local/share/gnome-shell/extensions inside a folder called volumeboost@extensions.eldruin.com Alternatively, you can download these files and execute this command

mkdir -p ~/.local/share/gnome-shell/extensions/volumeboost@extensions.eldruin.com && \
cp extension.js stylesheet.css metadata.json ~/.local/share/gnome-shell/extensions/volumeboost@extensions.eldruin.com

Either way, you will have to restart gnome-shell (Alt+F2 r) and enable this extension in Gnome Tweak Tool (or through the command line) to start using it.

Author: Diego Barrios Romero
Email: eldruin@eldruin.com
Public domain Copyleft 2012