i just found this posted on *****
try at your own risk :
Well... It was bound to happen... A downgrader for Asian PSP's!
WARNING!!!!!!!!! This could possibly brick your PSP, So Procede with Caution! We are not responsible for What happens!
It might brick your psp so be extreamly careful !!Yoshihiro and SXT are proud to bring you
The first downgrader compatible with the psp-1006 and psp-1007 hardware !
(the previous versions didn't work with asian psp-1006 and 1007 psp as the 1.50 eboot didn't want to run)
If you are willing to test it, go to our forums and give us your feedbacks !
Release Note: This is still a BETA version as it remains untested as we speak