I just bought a sony dru 820A to replace my Plextor 712 so I could burn DL disks, but when I try to burn a regular dvd disk is takes over 20 min. My plextor could do it in about 7 min. I updated to the latest firmware. 1.08 something. What else should I do to try to get the 16x speed this drive is supposed to deliver. I am using 16x verbatim dvd +R disks.