I have the subtank mini. I found that their factory coils are packed super tight with the japanese cotton. Here's what to do...Not only do you have to prime the coils, but they have to be broken in as well. To prime: drop some juice onto the cotton within the coil from the top. Let it set in and keep doing this until you see that the juice holes are saturated. Fill the tank, then put the tank on. Let it sit for about 10 minutes.
To break in the coil: Primer pull some for a bit without firing. Then start at a low wattage selection. Do more primer pulls but this time fire it a few times in succession as you are puffing on it. Let the vape produced escape from your mouth. Don't inhale at this point. It'll be gross. Gradually ramp up the wattage and do the same style of puffs. Once you get to the wattage you are comfortable with, yet again do some primer pulls before you give it an honest hit. You can inhale it now and it should be good to go.
The whole process should take 20 minutes to a half hour. Yes it'll waste some juice but your coil will last longer in the end.
By doing this I was able to run MAX VG with no problems.
Also worth mentioning: Some of kanger's coils are bogus from the start. They are hit or miss. I've tossed a coil after a day of vaping it as I would only get dry hits after that first day. Get the RBA (if it fits the nano). It'll save you money on buying new coils.