The game now includes:
Acoustic Guitar
Electric Guitar
Bass Guitar
Drums (improved)
Keyboard (new)

All the graphics for this game have been improved and there are now indicators so you can tell which note you're playing.

How to install:

PSP Phat:
Place the "psplay" folder in the "GAME" folder if you have 3.xx/4.xx/5.xx kernel enabled

PSP Slim:
Place the "psplay" folder in the "GAME" folder

New:
-Game now loads on both Slim and Phat, no need to download a seperate file for each system
-Keyboard
-Drum sounds
-Graphics (menus, backgrounds, etc)
-Indicator (points to the note you're playing)
-For some reason, that last couple releases included a lot of image files that were never used, those have been deleted.