If the iPhone user finds the volume of the iPhone too low, then there is a very useful Cydia tweak which can boost the volume up to 200%. The name of this tweak is Volume Amplifier.
Ever since the iOS 6 has been jailbreaked, various tweaks have been released every day on the Cydia community. And Volume Amplifier is one such tweak. The speaker of iPhone 5 is fairly capable but if the user wants to increase the sound further then don’t look beyond Volume Amplifier.