Everything on the 590 is upgradeable to the 620 parts. The big upgrade will be the ignition module. The 590 module is limited in max rpm whereas the 620 module is rev limited much higher and of course it's plug and play.
The one big upgrade is of course removing the top baffle on the muff. That will result in more grunt and a much more pleasant exhaust note as well. That and the Red beard oiled foam air cleaner and velocity stack.
The one big upgrade is of course removing the top baffle on the muff. That will result in more grunt and a much more pleasant exhaust note as well. That and the Red beard oiled foam air cleaner and velocity stack.