How to lower the firmware requirement in ELF and PRX files

How to lower the firmware requirement in ELF and PRX files

Example of lowering the firmware required for files compiled with the leaked 4.50 SDK (tested on 4.05) hex editing some bytes:

1. In the ELF section called "sce_process_param" we patch the reversed sdk version (there should only be one instance of the pattern):
 search for "01 81 50 04" and replace with "31 80 50 03"

2. In the ELF section called "sceversion" we patch the sdk version (multiple instances of the pattern will be found):
 search for "04 50 81 01" and replace with "03 50 80 31"

3. Resign it with flatz's make_fself.py or add it to a PKG with cfwprophet's Fake_PKG_Generator

4. Profit

5. A side effect of this is that if someone is able to dump games on higher firmwares (ex. 5.05) it SHOULD be possible to play those games in lower firmwares (ex 4.05) with this method, unless the games uses functionality added on newer SDKs