@taco bell: IME, OTC preparations are a lot more recreational. The pure HBr powder I bought online is nowhere near as enjoyable. It has something to do with absorption. As previously mentioned, cough syrups contain stuff like polyethylene glycol (PEG), glycerine (?) and alcohol, which causes the DXM to be readily absorbed into the bloodstream. Pure powder acts differently. It seems to come on just as fast, but the high is just not the same. More stupifying, more dead-feeling (emotions are wiped out to a greater degree), fewer visuals, less expansive/creative mindset. Basically, all of the negative side effects, without any of the good parts.
I now wish I had spent my money on actual cough syrup, or looked a little harder for MXE. But I'll still try a few more experiments with what I've got. I haven't tried mixing it with glycerine or anything of the sort, only alcohol, which didn't help one iota.
Maybe I've just reached the dreaded "50 Trip Limit," which would really suck