You can go as low as your mech + battery allow you to.
Mech. mods have their own internal resistance that shows as a voltage drop from battery to coil.
my mod drops the voltage of the battery by 0.2v.
but the largest contributor to how low of a coil you can make is determined by your battery amp rating.
all that info is usually supplied by the manufacture.
You can figure out the amp draw of a coil by doing some math with ohms law... there are many online calculators that make it easy, and all you have to do is plug in two variables. the calculator then figures out the rest.
as for battery drain, a 2000mah 18650 battery lasts about 3.5ml of juice....
my RSST(tank) is currently being run @ 0.7ohms
my ERA(dripper) has a dual coil that ohms out to 0.4ohm
which is still in the "safe" zone of the batteries that i use.
drilling out the air hole is also preferred by SLR users, as it counteracts the heat, and helps keep everything cool.
so to go SLR you would really have to dedicate a setup too it, as drilling out the air hole is a very drastic thing, and you may not like it otherwise.
NOW, i don't recommend doing this unless you do your research and practice caution, and better yet, have someone with you that runs these kinds of setups next to you. As an experienced pair of eyes can catch mistakes that a video wont be able to warn you about.
there is a reason that safety fuses and regulated mods cant run SLR coils, and that is something to always be aware of.
if you want to ask anything else, just IM me, and ill be happy to answer as best i can.
Just remember, the best vape setup is the one that keeps you off the stinkies.
