Yeah US game are import if you have a Jap system, the chip I suggest getting is the XO-10 from http://lan-kwei.com (You have to e-mail them about the chip since they remove it from there web-site) I have use it on my PS2 an have no problem with it. However you can not play original US PSX game on it you have to make a make a back up version and patch it with a Japan territory in order for it to work but as far as everything else it a great non-swapping mod for your system.
BTW it cost $30 lesser then ps2modchip.com
PS2 NTSC U/C v9 w/DMS3v9 Firmware v2.2
PS3 NTSC JP 20GB HDD
PSP NTSC JP