your pierce height should be 1/8th of an inch off the material. Cut height should be 1/16th of a inch off the material.
I would double check your cut and pierce heights with a set of gauge blocks. Or even a piece of scrap 10 gauge ( roughly 1/8th" ). There shouldnt be any reason you have to stray to far off the manual to get great results.
i use 60 amp consumables (hypertherm plasma) for everything i cut, 16 gauge to 3/8".
I have real good cuts using 60 amp tips on 10g. I just turn the plasma down to 40amps.