I'm using 6mg nicotine...I'm not sure if you're already stated it but what nic lvl are you using?
Hahah at one point I was convinced those guys were selling me 0 nic but I did in fact try another juice by that brand and it had quite the harsh hit.maybe its more down to an ingredient they dont or maybe they get their sums wrong.
mix up some 3mg gear like you have already mentioned and report back with your results.