i'm coolblue la ,
tuning are base on airfuel ratio , not too lean or not too rich ,
if you have stock ecu the air fuel ratio normally not perfect ,
so normally they tune down the fuel because of too rich ,
the best if to do it at dyno , use a wideband sensor a/f ratio meter ,
anyone can do tuning if he has a knollege to tune a ecu base on a/f ratio ,
tuning are base on airfuel ratio , not too lean or not too rich ,
if you have stock ecu the air fuel ratio normally not perfect ,
so normally they tune down the fuel because of too rich ,
the best if to do it at dyno , use a wideband sensor a/f ratio meter ,
anyone can do tuning if he has a knollege to tune a ecu base on a/f ratio ,