Try a bit of ethyl maltol in your mix- it has helped to take the rough edges from a couple of mine. Usually 1 drop per 2ml works nicely.
Another suggestion would be
vape wizard starting @ 1 drop per 5ml. It has a similar effect without adding sweetness to the mix.
Otherwise, try your unflavored base to see if the pepper is still present- I have heard that some nic has that bite to it, but I have never experienced it myself.