I don't think that you'll see a noticeable performance improvement with running tighter timings, and as soon as you deviate from stock RAM settings you can potentially enter into the realm of memory instability
.
Try 6-8-7-24-1T 1.65V
then if that seems to be stable:
try 6-8-6-24-1T 1.65V.
I don't know how well ECO's can be tweaked. I'm pretty sure that they won't overclock well.
Heck, most 1600MHz RAM kits these days are 9-9-9-24, so at 7-8-7-24 you have a pretty decent set there as is.