liquidzigong has released Custom Firmware 5.50 Prometheus.

Features:
It allows you without any modules, plug-in situations like the game to run 6.20. Procedures have been in the PSP-1003 & PSP-2000 on the test successfully.

Installation:
Warning, 5.50 GEN-D3 user installed may not be able to read the original SAVE.
Before installing the game first use sgdeemer plugin archive decryption, after installation you can use sgdeemer read the decrypted file back.
First, install 5.50 GEN-D3, however, download the package installation accessories. After successful installation, you can note the version number of the system into a 5.50 Prometheus.

Known to the normal operation of the original ISO:
KHBBS
MGSPW (Prologue do not crash)

Not known to the normal operation of the game:
patapon 3 DEMO

Thank GEN Team. This version of the vast majority of files from the 5.50 GEN-D3, you can call it 5.50 GEN-D4.
Thank risking a brick risk for my test program with some friends:
フ ェ the writing is ッ ス ク
LAA

FAQ:
Q: Why does the game start screen to turn red?
A: Yes, when adding the code to decrypt the original GEN-C is changed purple. In my firmware in a red, made in China.

Updated:
Prometheus module and has been used to improve the game's compatibility