I'm not sure what else you're expecting to get from it or what you think "the most" would be. It's subtle, and imo, even though lots of people say all kinds of things, I don't find it AT ALL comparable to any kind of opiate in terms of effects, and while I haven't taken every opiate in existence, I've taken most of them. Sedation, drowsiness, and feeling relaxed is what I'd expect from kratom at high doses (and 15-18 gr is indeed a high dose), but I cannot for myself compare it realistically to any opiate I've ever taken. eta: actually, if I took 15-18 grams, I'd get the wobblies and feel like crap. I've only tried that much twice and regretted it both times. Very unpleasant. So ymmv obviously.
Now, in the interest of full disclosure/the bigger picture, I'm only a month out from a four-year daily pod habit (and before that it was pills), so it's possible that it might treat some people who are kratom-naive and not opiate-dependent or very recently clean differently than it treats me. But the people I hear saying "yeah, man, kratom is like [fill in the opiate]" are usually not too opiated prior to that. But if you can take a lortab and feel it, then maybe it will feel different to you, I don't know - it's probably been 8 years since there was any point in my taking a lortab. But it's also possible that you need to adjust your expectations. Even experienced kratom users will often say that it's a lot more subtle and "clean" than various things it gets compared to. And I know personally that I have often enjoyed kratom more when I take less of it - it's kind of something you have to cooperate with and ride along with, if that makes any sense at all, rather than being a "take x amount and get x effect" button-pushing, predictable type of thing. You can't force it, I guess is part of what I'm trying to say (I don't know if that makes sense to you or not, hard to explain).
