I really like the stock timing on these things. When doing emmisions testing I found that a lower timing of 14 degrees (which is still within spec) lowers a lot of emmisions.
Timing adjustments does make some inprovement over stock. Most noticeable with a tuneable ECU like Hondata or the likes.
Look here
That dyno shows only a change in ignition timing tuning. The base timing effects very little and when you are at WOT, the timing is read off ECU anyways like the fuel maps so it doesn't really matter.
So unless you have a tuneable ECU, I'd just keep it stock within spec.