I've read that several people had problems running DVD9 games, something about the laser not being powerful enough appearently. I was planning on getting a 10 piece dvd9 cake, but they are much more expensive compared to the single layer ones. If they are not going to work on my ps2 I will not buy any. I was wondering, is there a way to determine which models have problems with DVD9 games? Is it just random? By the way, I have the Guitar Hero World Tour disc, which as far as I know is a DVD9 game (it is the original disc, not a back up). I have never used it, but would it be safe to assume that if that disc works, then the DVD9 backups I created must work as well? One last thing, would using a DVD9 backup damage the PS2 in any way possible?