in my opinion when working within the limitations of a mech, the best way to get an instant huge rich thick vape is multiple
coils.
to make it heat faster with only ~4 volts peak you need either shorter coils-or- smaller gauge wire-or- multiple coils.
a shorter coil will burn the wick faster and give a less satisfying vape,
smaller gauge doesn't have the same flavor and vapor production,
and multi coils are a pita to build, and wick, and rewick, and also to even fit into many of the better BF atties out there but
to me the only way to get really top performance with a mech is a multiple coil sub ohm build.
the rm2 chamber is very tiny, it's great with a single coil but might be a bit too much for duals, although duals can certainly be done. to do duals in an rm2 I would say the best way may be to drill another air hole opposite the first coil and mount the second coil opposite the first, if you get the right airflow it can work well BUT the tiny chamber with duals will really enhance the flavor, to the point of too much even for some. this is why multi coil atties generally have a significantly larger chamber
you don't have to go with multiple coils, you can get a great vape with a single coil too, something like a 12-13 wrap .055" ID 28 gauge coil will give a great vape, comparable to duals, only thing is it will be quite a bit slower on the heat up than duals would be. that's the trade off there, to get instant big vape that doesn't toast the wick in 4-5 seconds you need multi coils. a single short 4-5 wrap sub ohm will give you the speed but burn up with too long of a hit and not give as good of a vape but still can be good as long as you take relatively short hits, and a high wrap count micro of 30-32 gauge will be fairly quick and give a decent vape too, but not the same as 28 gauge or less, many find 29 gauge to be a reasonable compromise.
I know I haven't given you much of an answer but some things to think about.
also, if you really want to use a larger atty for multi coils on a non lp grand you can use a 510-510 extension and mount anything you want on there including a AFC cyclone, or then theres always just taking a grinder and sander to that reo, that's how the LP was born in the first place
