I dont think mini's with the older poppet should ever be unuseable, most people get them working fine.Sorry to threadjack but where can i get the Mini sent off to in the Uk to have the poppet mod done. It was totally unuseable at the p.a
I would adjust your velocity adjuster and dwel to the recommended settings and then adjust your input pressure untill you get the velocity you want.
One of the main reasons people are having trouble setting up mini's (I believe anyway) is that the gauges are crap and will display anything upto 40psi difference from the actual pressure. Mini's should be run strictly between 180 and 200 psi to work properly which means if you got a crap gauge you could actually be trying to run it at 140psi which it simply wont work at.