Sony has a security system called DNAS. It prevents the use of any kind of non authorized combinations (USA Software with JP units or euro, JP software on US/EU units) and some modchips are also detected. If you are spotted as modchip owner your PS2 serial number will be blacklisted on DNAS server. Since you will be logging on a japanese DNAS server, you probably will not earn a ban but it will surely don't let you even start the software installation. After the software is installed you need the HDD browser software for your PS2 region, as you need it to boot the POL software.
I use a SCPH-30000 japanese unit with BBNavi.30 for FFXI.
The same HDD can be formated and used in a US unit with the HDD utility disc provided on the FFXI Beta package (It's same as the 1st HDD disc for japanese units, which was originally released in 2001)
You also can't install PS2 FFXI from copies. Thanks to DNAS.
