Ohh, sorry for that!

To get more hashes you have to do someting with memory. Try this timings for Micron 777000000000000022AA1C0073626C41B0551016BA0D260B0060060004061420EA8940AA0300000 01914292EB22E3B16
But -mt 2 option is better than nothing.
I belive your 31.4MH/s is a very good result and if its stable you'd beter just stop
The most unpleasant moment in high coreclocks and memoryclocks is high power comsumtion. Its unprofitable by any means exept free electricity.

Now waiting for UnclWish to proof stable 33.5-34.1MH/s@110W from the wall for Polaris cards. Now we know all settings neded except timings to get the same result.
By the way Sapphire RX 580 8GB Special edition is a Top Polaris card and I belive its quality enough to get the best possible hashes. Hope UnclWish wil share timings with you to make a fair experiment.