Maybe he means level 5 from the
scale I saw on shroomery? This maps to +3.5 - +4 on the Shulgin's scale.
^^ Welcome to bluelight! We're always glad to see new people here.

People here use
Shulgin's scale. The 'shroomery scale' is suitable only for visual phenethylamines / visual tryptamines, and not every psychedelic produces many visual effects even in high doses. Shulgin scale is good for many classes of psychoactive chemicals, because Shulgin studied not only psychedelics but also emphathogens(and I guess even stimulants, though he wasn't focused on them). Also, difference between 'Level 5' and 'Level 4' seems to be
quantitave, whereas difference between +3/+3.5 and +4 is
qualitative difference.
You can't reach ++++ only by taking more, you should be in proper set&setting. ++++ states are rare, and many psychedelic users(me, for example

) never experienced it.
OK, as for you question. I am sure we already have several threads on this topic, but I can't find the most recent one(it is difficult to search for "++++" sequence).
Here are other topics I found, check them, they may be interesting for you:
Honored to be "chosen" ++++ (plus four experiences)
[LSD Subthread] Spiritual Experiences / Plus Four / ++++