the problem here is that you are using high nic with a high airflow cloud chasing coil. It's that simple. I vape 36mg in my MTL devices and never cough, and can't handle more than 6mg in the sort of coil you are using.
PS it' not because it's a sub ohm coil, it's because it's a direct to lung coil. I frequently use 36mg in a 0.15 sub ohm nickel coil in my nautilus (triton mini coils), and it's not harsh at all.
it is indeed also possible that the PG is bothering you.. although when i coughed my guts out in a high airflow coil, with 12mg, i was using 100% VG juice, 0 PG. I really feel the problem is that you need a nice restrictive MTL setup to use high nicotine.. for the one you have now, go with 6mg high VG juice.
PS it' not because it's a sub ohm coil, it's because it's a direct to lung coil. I frequently use 36mg in a 0.15 sub ohm nickel coil in my nautilus (triton mini coils), and it's not harsh at all.
it is indeed also possible that the PG is bothering you.. although when i coughed my guts out in a high airflow coil, with 12mg, i was using 100% VG juice, 0 PG. I really feel the problem is that you need a nice restrictive MTL setup to use high nicotine.. for the one you have now, go with 6mg high VG juice.