Gonna assume it's a VTC4, 20A battery (probably a safe assumption).
At that resistance, the lowest you could theoretically build is .22 ohms. With a fully charged battery, this would put you RIGHT at your amperage limit. You don't want to be at the limit. It's a good idea to allow at least 30-50% headroom to allow variances in the battery/coil/other random factors that you can't exactly control. You can plug the numbers into Steam Engine to figure out what resistances produce what amperage. For example, you can plug in the voltage of your fully charged battery (4.2V) and the resistance of your coil. Steam-Engine will tell you what amperage that's producing, and what wattage that's producing. You can switch the variables around -- the calculator is very dynamic.
Your limit is 20A, but I would suggest keeping it lower than 13A -- that's a metric "****load" of power man.