If you install iRadio, there is a file in the app's directory called: SystemSoundMaximumVolume.plist
I followed the directions to move that file into place over the Default apple one
and it increased my volume considerably.
So intall iRadio, then do what its READ ME says...
This is because default preset for volume settings was set too low inside of the
Celestial framework. To cure it follow the steps below:
1) download
http://subband.com/~mewse/SystemSoun...umVolume.plist
(if missing in the distribution, or place the file included)
2) upload this file to your iphone (via scp)
3) mv ~/SystemSoundMaximumVolume.plist /System/Library/Frameworks/Celestial.framework/
(replace the old one inside Celestial.framework)
4) restart, and you're good to go!