I have currently installed some Mac stagered exhaust pipes on a 84 VT500c. I have also replaced the air filter with a K&N. When installing the Mac exhaust they claim that i do not need to rejet or adjust anything. The bike to me has always seemed to run a little lean to me. What i am wondering is can i richen things up a bit by adjusting the air/fuel mixture screws or am i going to need to rejet? Also would shimming the needles help the bike run a little more rich or is the only way to change the jets? Thanks for any help you guys can me on this old classic.