I mainly use 28ga in my Kayfun's, a 6-7 wrap over a 2.5mm mandrel should be 1.2-1.4 ohms. I really like it and it makes a Provari very happy! While you are shopping look at the Coil Master V3 coil winding kit. Watch the videos, there's a bit of a learning curve, but I wish I'd had one years ago! Cheap, makes great coils and I love mine! For about $4. you can buy a single mandrel or for about $12 you can get the whole kit.