Wrong. But seen as this is piracy, we better not discuss any further.
I have an original gt4 copy here. So if I would like to make a backup it shouldn't be considered illegal.
I tried to burn a full gt4 dvd9 image with a dvd+r dual layer burner. It burned fine, but in the ps2 it always failed to load after the "copyright screen".
So i googled a bit and found out that this is because dvd+r dual layer discs are for Opposite Track Path recording while the original Gt4 disc is made using Parallel Track Path.
So either one would need a rip patch that makes it fit on a normal 4.5gb disc or dual layer discs(dvd-r?) that support ptp, which arent available yet iirc.
edit: anyway, gran turismo4 is well worth its money even if you buy it, its the best racing simulator out there on any platform