Hey Osake! I have extensive experience with 4-aco-dmt.. I have never had any of the breathing occurances you speak of with this chem, but then again i havent with mushrooms either..But yes it's VERY normal to feel no "rush".. And "tripping sober" is a wonderful way to describe low-medium doses on this chem. For me, when I start peaking its almost anti-climactic.. Like there's some huge buildup and then once I peak this huge weight is lifted off and I feel totally lucid and clear. Aces is one of the only psycedellics I feel comfortable to take a dose almost anywhere, Ime it's consistently a rediculously clean trip and can offer LOADs of insight if used in the right way.
I <3 aces

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