1g phenibut is great with kratom during the day.
At nighttime, I was shocked when high dose kratom, and a few bong rips, or just one dab would have me nodding. I have very high opiate tolerance, and there has to be something in either weed or kratom that causes the potentiation of both. There is a rumor that they both work on your 5HT2 receptors. If so, this would definitely explain it. There's been times the combination has had me in a deep opiate like nod, and other times when it's almost been a psychadelic type, first time smoking like experience. Sometimes the weed potentiates the kratom, other times the kratom potentiates the weed it seems like.
The only other thing you can do is buy UEI, gold reserve, or FST. Be wary though, if you take too much of these extracts, you will get very sick, dizzy, and nauseous for a good 6-8 hours. Redosing will also cause you to get very sick, so dont bother either. I also have gotten legitmate opiate withdrawals comparable to a 60-80mg of oxy per day habit off of UEI. Very powerful stuff, very expensive, and if you wanna head this road, you may as well just buy some dope unless you have a drug test to pass.