The only reason lean is even in the limelight is because rappers have blow it way outta proportion. I understand Houston rappers like Pimp C using it as a regional tradition to catch a buzz, although Pimp C died on the shit + xanax and something else I think due to sleep apnea + respiratory depression and so did A$AP Yams (Xanax + lean). I would be pissed if my life ended due to a shitty concoction like codeine w/ promethazine. Not that both drugs don't have their place in recreational drug use, it's just not what it's made out to be. Lean is a more-than-mild opiate buzz with a sedating AH.
Since getting Hep. C from sharing needles in my past (whilst shooting IV heroin and cocaine) I am a poor metabolizer of codeine, therefore it barely converts the codeine to morphine which is a huge part of the euphorigenic/analgesic properties. This is now the case with tramadol now too, I don't really metabolize trams to O-DT which is unfortunate, because I got to enjoy the unique, blissful-serotogenic high from tramadol metabolizing into the more mu-agonist effect of O-DT only a few times. Now I just get anxious and jittery, and on-the-verge-of-a-seizure like activity from tramadol's SNRI properties, which I'm not a fan of at all. I need to try straight O-desmethyltramadol (O-DT, M1, O-DSMT). Anyhow, I digress. LEAN IS OVERRATED.
Codeine is only useful for those with little to no tolerance in most cases (some potent opioid-using individuals still enjoy high-dose codeine possibly due to their metabolism) or staving off WD in addicts. Still not particularly known as a very euphoric opiate. Might as well just go for morphine IMO. Morphine is the gold-standard of opiates/opioids. Liquid morphine or liquid oxy (OxyFast, which I've had the luck of obtaining and using at ~60-80mg in some sprite whilst in acute IV heroin WD's, brought rapid, euphoric relief)