DXM sigma questions?

[dood42069]

I will give some background on my drug use.
I have done DXM a lot (50-60 times) I have been from low first plateau to high third (700 MGS) It has also been 2 months since my last DXM dose.
I have done 1.25 MGS of alprazolam
I have done 20 MGS of zolpidem
I have done 100 MGS of codeine, 30 MGS of hydrocodone and 20 MGS of oxycodone
Finally I have done 60 MGS of adderall
I am 5'9 and 130 LBS (55KG)

Now I have several questions about plateau sigma.

1) Should I explore fourth plateau first?

2) How damaging is it?

3) Approximately how long does it last?

4) How should I reach it?

Thank you for any replies!