I tried this a week ago and was very surprised with the results. For one thing, I got my Kava at the local health food store, so I was expecting it to be basically inactive. I mixed it with about 3.5g of Green Borneo, and for the first time in months, I actually was nodding out, something that kratom alone has never done for me. In fact, Kratom doesn't do a damn thing for me regardless of how high or low I dose nowadays but get me well, which made me wonder if it was the kava alone responsible for the effects rather than the synergy.
But yeah, it's a blast.. I will say, be careful with how you dose your kava. My bottle said to take 1-3 pills or something along that line, so naturally I multiplied that by 8x, and have to say that asides from nodding, I don't remember much of the experience. Kava is some real shit, you can get pretty intoxicated on it..IMO (and keep in mind my experience with it is pretty limited) it's got similar effects to maybe a low dose GHB and the muscle relaxant properties of alprazolam.