I am burning data DVD-R's on my PowerBook which I believe has an 8x SuperDrive that writes at 8x, correct. For some reason it will only let me burn at 2x, even though I have an 8x burner and the DVD's can do up to 16x.
Firstly, you cannot compare CD and DVD read/write speeds because they're completely unrelated. The 8x speed is referring to DVD read speeds. 2x write speeds seem quite normal to me. 🙂