FYI, New Firmware Upgrade for DRU-500A, DRU-500AX, DRX-500UL, and DRX-500ULX

http://sony.storagesupport.com/freeupgrade/

Allows recording at 4X on appropriate DVD+R media.
Improves reading and writing performance and reliability.
Reduces vibration noise for the discs with unbalance or eccentricity.

Have not been able to test; good luck, Kevin.