Right, before I start with this tutorial let me just say:
I TAKE NO RESPONSIBILITY IF YOU MESS YOUR PHONE UP. Don't do it unless you are confident of success.
Don't break your phone for the sake of showing off.
Okay so let's start.
1) Press the dial button on the home screen and type 3845#*990#
---DON'T PLAY WITH ANYTHING IN HERE EXCEPT WHAT I SAY CAUSE YOU WILL BREAK YOUR PHONE.
2) Go to Device Test. (Number 2)
3) Go to Sound. (Number 8)
4) Go to Audio CAL Tool (Number 7)
5) Go to SOUND CALIBRATION (Number 1)
6) Go to CHANGE SOUND DB
7) Change snd_device_type to SND_SPEAKER_MEDIA
8) Change snd_method_type to METHOD_MIDI
9) Change Item Title to rx_volume_db7(dec)
10) Where it says Set Data at the bottom, press and a number pad will come up, type 900, then press ok. DO NOT PRESS BACK.
11) When you've pressed ok, press -(Minus) (left selection key onscreen)
12) Press back (right selection key onscreen) DONT PRESS "C" OR HANG UP CALL BUTTON
13) Finally press Write SND DB to EFS, then when that's done it's stuff exit to the homescreen.
HAVE FUN.
And once again.
I CAN NOT BE HELD RESPONSIBLE FOR ANY DAMAGE YOU DO TO YOUR PHONE, THIS TUTORIAL WORKS PERFECTLY. DONT COMPLAIN AT ME IF IT DOESN'T WORK FOR YOU.