Noobz just brought us the 3.03 downgrader, but they've also released a port of Dark_AleX's HEN (Homebrew ENabler) for the 3.03 firmware in case you don't feel comfortable with downgrading or just want to stay on 3.03.
You will still need the unpatched GTA: LCS UMD to run HEN on 3.03, refer to the README contained in this archive or if you have any questions or feel free to ask for help in our forums.
Download HEN for 3.03
You will still need the unpatched GTA: LCS UMD to run HEN on 3.03, refer to the README contained in this archive or if you have any questions or feel free to ask for help in our forums.
Download HEN for 3.03