u clearly dont have the stinger voltmeter set right... they are very very accurate..
whoeever said they Are .5 volts off... didnt pop the cover off and adjust it..
and get some fuses in there before you burn something down with that stock 80 amp alternator..never run a system without fuses or circuit breaker...
how do you have then battery hooked up? directly fed off the alternator? or off the under hood battery..
also do the BIG 3 upgrade thatll help a bunch also