OC questions

I have Rx 470 8 Samsung and Rx 480 4 g elpida
I do dual mining ETH+dcr
I want to know if I will get the same result (27.5 mh/s)
What is safer to do
Copy the 1750 strap to the 2000 and set the memory frequency to 2100
Or copy the 1625 strap to 1750 and 2000 , set the memory frequency to 2025

And for the 480 a get 29/30 when I copied the 1500 strap and set the memory frequency to 2100

How to enhance this cuz I have a friend who gets 30 mh/s from 470 4 g Samsung
But wouldn't tell how

Thanks