Ehh... what do you guys mean by modified PS2?
I'm not sure if anyone asked already or not.
Just Google it. Game consoles normally have a regional lockout to prevent use of imported software, and also an authentication protocol that prevents burned discs from booting on them. A modified PS2 has those mechanisms bypassed or disabled in some way to allow you to use one, or more commonly both types of software on your system.
PS2s aren't normally sold with those functions disabled, so you'd know if you had paid someone or installed the required devices yourself.