I'm a bit confused here
Tried putting them on seperate IDE channels, they're now set as Device 0 = primary master, device 1 = slave. Pioneer set as Secondary master, NEC= secondary slave. I can still only write at 4x. and now if i write at "8"x on the pioneer
What device are you reading from? If it's a DVD-ROM on the primary channel then OK, otherwise if it's from burner to burner then this is completely wrong for on-the-fly copying. For burner to burner copy/burn you must have these on separate IDE channels.
However, some apps, like Nero I think, will do a read test first & then limit burn speed to match the speed of the reader.
If you don't have a DVD-ROM I think that without any modified firmware on either burners that have riplock removed then your rip speed will be limited to 4x, so will your burn speed. The Asus E616 is a good DVD ripping DVD-ROM.
Let's be very clear that whatever you do the reader MUST be on a separate IDE channel to the burner.
BTW you system is well up to spec for this.