via http://psp.dashhacks.com/2012/04/06/dump-firmware-pspgo

This morning neur0n dropped a little something for the PSPGo owners out there. This is a method of dumping the 5.70 Firmware. Firmware dumpers are nothing new to the mod community but the importance of this one is that it is a step in the right direction to develop a downgrade for the PSPGo. Be aware this is only for the 5g version of the PSPGo and nothing else

http://www.sendspace.com/file/p0jxkk