Dont do it,
Trust me , if you get a bad reaction its horrifying,
I know from takng 200mg and 800mg dxm 9 days apart when i was a noob lol.
use this as a rule of thumb
DXM plateau 1 = 1 week wait
plateau 2 = 2 week wait
plateau 3 = 3 week wait
plateau 4 = 1 month wait minimum.
stay safe.