A level 4 experience doesn't very often only involve 2.2 grams, but here it goes.
I am 22 years old, and 160 pounds.
I used to take huge doses of lsd, dxm and shrooms if the time was right. The kinds of doses that are very very serious, and are often avoided. However the following experience helped me understand just how far I had gone in my past experiences, and helped me to understand some limitations I must now abide by.
So......I ate 2.2 grams of typical, good dried shrooms(cubs) by myself. It was under controll for the first 10 min after ingestion, while hiking by myself in the forest. Then the 20 min. mark became sort of scary (quite early in the experience). This used to be(these days, perpetually less-so) the kind of dose that was interesting when alone as well as being lots of fun when with friends. This time, the 30 min mark was to be feared. After one hour of harsh realizations about where this trip was going, I was returned to a place I thought I could only go on a "high dose" of either shrooms or ayahuasca. The intensity was ridiculouse considering the dosage. If ya cant hardly see whats in front of your face when your on 2 grams, then you are an exception to the rule. Ego loss and the anxiety that follows is one thing, but I couldn't breath correctly because breathing was interrelated with audio, visual and cognative structuring for the first hour and a half, fostering the ultimate primal, bodily anxiety. This oxygen deprivation (forgetting to breath), is an intigral part of that which propells me to the highest hights before "almost" passing out, only to then breath again, thus restarting the cycle(a part of many cycles). Usually though, this happens only on pretty massive dosages, and is expected, but not this time on this low-medium dose. I meandered throught the forest allowing it to perpetuate my thought patterns untill I had to deal with the unexpected re-emmergence of these high-dose symptoms. In about two hours I sort of came to, but was tripping for about 8 hours after this, and was weirder than ever the next day. Oxygen deprivation helps fascilitate a strange, unintentional use of language which was a reacurring intrusion on my normal thinking during the experience as if it were a gate-way to seperate intelligences within myself. Some of this effect lasted for about three days, gradually waining.
I want to share this story because, I feel that for some, once ego, hearing, vision and much of the body has been thoroughly destroyed during an experience(the soarce of most bad trips), there are other more intimidating psychosomatic barriers between ourselves and the answers to the mysteries that attract us. The dose required to physicaly freak out like this is different for everyone, and the dose becomes very hard to define when you are an experienced user of hallucinogens. However, this often torturous realm is better off experienced fully, rather than avoided, because this near-total loss of mental/physical controll is about as interesting as these drugs can get.