latest nvidia kernel boost (not straps but kernel!) made it on par with phoenix.
Now we need the same for polaris. Phoenix has faster kernel 1 and kernel 3, and the speed now is the same due to straps in Claymore's
If you (some way) bring those straps to phoenix it will be even faster.
For example, rx570 8gb micron 1220/2250@855mv (83watt gpu-z) is capable of 34.4mhs with such combination.