I usually leave them all ON unless I burn decent media (eg Yuden, Japanese Sony and Maxell, Verbatim, MCC, etc). In these cases I turn off SB for known media (which is the default setting anyway), and if I'm pretty sure about the quality of the individual batch I turn off WOPC too. I also use overspeed a lot with RICOHJPN R01 002, these are red top Datawrite Classic x4 DVD+Rs and they overspeed up to x12 in both my 1650 and 1655 with great quality scans of 96+. A great result on a very cheap media. No two writers are exactly the same however, you have to find the sweet spot yourself. Just make sure you don't burn under heavy system load conditions as this can impair the burns (especially on slower machines).