>> With freeBOOT v0.02 and XBReboot v0.05 being released opening our retail 360s (with older 2nd bootloader/CB) to run unsigned code, people are starting to experiment stuff.
Surazal on our forums found out the difference between a demo and full Xbox Live Arcade game is only a few hex-edit away:
Find a copy of Yaris (this game was chosen as it runs everywhere as full).
Open the pirs file in your favorite hex editor (filename was FB9310B8893A3FD01C443A29AC246493393E399558 )
Copy everything from 0x22C to 0x25F inclusive.
Shown as selected on this image (guess you don't need to find Yaris if you want to just copy the values highlighted).
Open your destination (in my case Castle Crashers filename: F9432A7FE407A3C196C95D0FFD4A540937FD4EEC58)
select 0x22C, and paste (overwrite, not insert). File size should NOT change.
Note that this is (probably) illegal if you didn't actually buy the actual Xbox Live Arcade game. But as running a "homebrew enabled" Xbox 360 is not (and probably will never be) safe to connect to LIVE this is way to make your Arcade games you bought play in full version on your homebrew Xbox 360.
2 tools to help you auto-patch arcade games have been released as well:
* Arcade Demo to Full Converter (adfc) v0.1 (by FreeXeX360)
FreeXeX360 :: Arcade Demo to Full Converter v0.1
Usage: freexex360-adfc.exe <LIVE file>
* Yaris-Swap v0.02 (by zouzzz)
Yaris-Swap use your [Surazal's] tips (for LIVE and PIRS files). If someone can test it.