running lean means he's a goober and didnt tune the car like youre supposed to. thats like people who bought the power fc from mwr and complained cause they didnt get a huge peak power difference and their car ran rich.
staffords civic ran a low 13 at lacr which would be good for a high 12 at sea level. there's nothin wrong with that kit. if you dont take care of it though you wil have a problem. thats true for anything though.
if you dont get a SF kit get the c2gas kit. it's way better then XS engineering.