Sony DRU-510ak Formware 1.1a and burn time

[Jongi]

When I burn to 2x DVD media Nero will show a burn time of around 30 minutes. When burning to 4x DVD media Nero will show a burn time of around 15 minutes. Assume the media is Verbatim DVD+R.

However even when Nero indicates a burn speed of 4x and estimated time of around 15 minutes when using 4x DVD+R, the time it takes is aways that it takes to burn at 2x.

Am I missing something here?

NOTE: I upgraded the firmware using that indicated for the DRU-510a but the problem was in existence before I upgraded the firmware.

[Jongi]

Is it likely that the suggestions in this thread could help me?