Nec 65750a - firmware variation

using the 6750a drive with liggy firmware 2.01 in normal ATA i have been untl recently been burning taiyo yuden value line 4x DVD-R.

they burn flawlessly for me and at speeds up to 6-7x under normal circumstances without error using nero 6 …the last version update.

i can no longer get value line 4x and so purchase premium taiyo yuden 8x dvd-r’s.

i now find under the same circumstances the new dvd’s will burn usually at 2x or soemtimes up to 4x but never at the 8x.

thinking the firmware might be a little old for this 8x dvd i changed to firmware 2.42 normal un modfied and find the speed has improved slightly but nothing close to the 8x or better i expected.

does anyone have any thoughts on this matter?