I just tried playing gt3 on a ps2 with the dfgt and cannot get it to work(probably because it doesn't), the gas and brake don't function as they should, not even close. It is strange because you can calibrate them just as you can the wheel and everything seems fine.The little bar starts at 0 and goes up to max for both as you press pedals. I tried every which way of pluging in controllers, unplugging controllers, all that, both usb ports etc etc etc.
I can play gt4 on the same ps2 with the same dfgt though, I've done that several times.
I wonder if it's because I'm using a slim but I seriously doubt it.