Sportsters come jetted richer from the factory to begin with, so per that article, just uncap the mixture screw. Install your pipes, get the bike warmed up, then adjust your mixture screw and reset the idling. Ride the bike and see how it does. If you don't run baffles or lollipops you're going to lose low and mid range torque. Study up on plug reading and see how your plugs look. Then you can play with the jetting if you're still not happy.