Move over Dark_AleX (unless it's yet another alias of his like 'M33' lol, as the HX-1 Recovery Menu shows M33), Spanish developer _HellDashX_ has released a new PSP Custom Firmware based on Sony's latest firmware update - 3.72.
According to the author, all features from the previous M33 release have been left intact and minor code changes were made to support the 3.72 kernel.
Installation (must be currently running at least 3.71 M33 or 3.71 M33-2):
* Create a folder called UPDATE in PSP/GAME
* Copy umodule.prx and EBOOT.PBP to the UPDATE folder
* Download the official firmware 3.72 update, name it as 372.PBP and place in UPDATE folder
* Run the 3.72 firmware update from the PSP Game menu. When the update is finished, you must follow the on screen prompt to press X and restart your PSP.