I'm probably going to be of no help whatsoever, but here goes lol.
I always vaped my 2.2 and 2.5ohm coils on 4.3v. It was a good vape for me. I even vaped the 1.8ohm coils on 4.2-4.3
Since then, I've rebuilt my Protank Mini 2 coils with 1.6 ohm microcoils using 28g kanthal and cotton. AMAZING vape, but I use 11w (4.2v) on my MVP 2 and 15w (4.8v) on my Vamo. Best vape I've had yet. Since the MVP only goes up to 11w, I have also used the 5v setting and it's awesome.