This is the New GOD II Custom Firmware (CFW) for All PSP models including Go. You can use this on 6.60, 6.39, 6.35 and 6.20 Official Firmware (OFW) or CFW. After downloading the file provide proceed with the following.
Step 1: Extract files and you will see the following folders: 6.60 GOD II, 6.39 GOD II, 6.35 GOD II and 6.20 GOD II. Open the folder for your firmware and inside you will see Permanent for PSP 1000 and 2000v1 models and GOD and FastRecovery for PSP 2000v2, 3000 and Go models.
Step 2: After selecting the folder for your firmware, For PSP 1000 and 2000v1 models take the Permanent folder and place it in the ms0:/PSP/GAME folder and for PSP 2000v2, 3000 and Go models place it in the ef0:/PSP/GAME folder.
Step 3: Run the installer from GAME on the PSP for 1000 and 2000v1 models and your done. On the 2000v2, 3000 and Go Models Run the installer from GAME and then set up your settings and use Fast Recovery and your done.
NOTE: DO NOT USE PERMANENT ON MODELS HIGHER THAN PSP 2000v2