Hi, for my billow I make two 28 gauge 8 wrap micro coils which gives me about a .4. I vape that at around 20 watts and I'm pretty happy with that build. To make the micro coils I compress my coil with tweezers then I fire the coil with a butane torch for a few seconds, then I submerge in cool water. This gives me a perfect micro coil. Don't fire the coil too long or it can become brittle. Just a couple of seconds. You can Try this with your gauge wire and see if your happy with the results. I hope this helps out. It gives a tasty vape with loads of vapor. Hint, make sure both coils are firing at the same time. If their not, adjust them until they do. I adjust by squeezing the coil with tweezers after its heated. It works well for me. With the billow as with all dual coil builds, it's important for those coils to fire together. Best wishes ps. Know your batteries limit and use ohms law to insure you don't go over the batteries Amp limit!! Important, always practice safe vaping. If you don't like doing the math, there is a app called ohms law that will do the math for you.NEVER GO PAST THE LIMIT OF YOUR BATTERIES. vape safely . If .4 goes past the amp limit of your batteries, do NOT attempt to build that low.always be safe.