Since you have mods (custom code), you will need to run the autoupdater package for each version. It works pretty well, but you are pretty far behind. Look here: http://sourceforge.net/project/showfile ... _id=194469
If you click the phpBB 3.0.1 link you will see a package entitled phpBB-3.0.0_to_3.0.1.zip. You will need to start there.
Click the phpBB 3.0.2 link and you will see a package entitled phpBB-3.0.1_to_3.0.2.zip.
Then you click phpBB-3.0.2_to_3.0.3.zip to get the final package.
. . . if you need them.