I am currently running open Harley pipes and 130 mainjets to tide me over. Runs fine too! But I have a jetting kit I still haven't used by "6 sigma" the kit wants me to shim the needle and use a 115 120 or 125 mainjet depending on what my bike needs (supplied all 3)
Could someone explain the difference between these 2 approaches and what is the benefit of the race kit over just jetting?
My airbox is stock btw the kit still suggests doing it this way. It has setups for airbox, pods, and airbox removed snorkel
Thanks in advance
