I would assume you are changing you a/f raitio with an AFC the only right way is on a dyno with a wideband O2 sensor. If you "play" with it and dont know what your a/f readings how are you going to tune? Lean is bad= detonation and permanate motor damage. Rich is slow and= bad gas milage and idle not to mention power loss. Have it done by a pro with the right equipment and enjoy:)