People get sick with yopo.  This seems to occur regardless of the method of administration.  It may be a result of a non-bufotenine chemical in the seeds, or it could just be a side-effect of the serum concentration of bufotenine changing so rapidly as the drug gets taken up.  SWIM didn't vomit when he snuffed the seeds, but there was substantial nausea on the come-up.

I'm not sure what your recipe is, but 1:4 lime to yopo seems like the most you could possibly need.  Lime is pretty alkaline material.

Also, just to be clear, not everyone enjoys bufotenine.  It's definitely not going to catch on as a recreational drug.  That said, SWIM found it a worthwhile experience.  Once, after taking the snuff by itself to become acquainted, he took the snuff on the plateau of a mushroom trip, and found the two to complement wonderfully... there's also something a little poetic about pairing 4- and 5- hydroxy-DMT on a visionary jounrney.