How to Install custom firmware on a PSP « PSP :: WonderHowTo
Modded Sony PSP 3000. 6.61 CFW Mod. 128gb. Charger and Battery - Etsy Sweden
PlayStation Guide
Infinity 2.0 released for the PSP, allows for persistent CFW on all models of PSPs on 6.60 and 6.61 | GBAtemp.net - The Independent Video Game Community
Picked up a PSP-1000 on firmware 1.0. Any reason to NOT be on 6.61? : r/PSP