Yeah it could be the fact that the gauge isnt as good as the EBC. fuel cut is also different car dependant could give minor room for error Yes ive heard good reviews! any good brand will be fine defi,hks,apexi, blitz, greddy, stiri. ive seen the cheap prosport and autogauges give poor readings. Once you have a good gauge in id go off that and aslong as the gauge is holding the pressure you want then the EBC will be setuup correctly