How to downgrade your PSP Firmware with Chronoswitch - Darthsternie's Firmware Archive
Custom Firmware freezes PSP 2000 and when I restart it the version is still 6.61 and has not updated | GBAtemp.net - The Independent Video Game Community
PlayStation Portable (PSP) Go (N1001) - fully working, with 1 or 8Gb memory card | eBay
Got this baby. System version is 6.39. Never been hacked. What should I do to hack it? 6.60 or 6.61? Confirmation button is O. Can I switch it to X with Infinity
Easy Mod For Any PSP/ PSP Go / PSP Street 6.61 CFW Permanent In Just 8 minutes - YouTube
Davee's 6.61 Infinity project update - PSP Go
Release: Infinity 2.0 – Enables Permanent 6.6x Custom Firmware for all PSPs! - Wololo.net