I am experiencing the same problem, I tried several different plug in system controls to try to remove the surging from mine. RC Extreme and Power Commander III, still surging. I took it back to Harley and they put the Race Tuner to it, still surging. Now they say it needs dyno tuning....... I catch a rash of crap because I put the exhaust (Rinehart true duals) and Super Sucker on myself, that's like bolting on a mirror or a highway peg and shouldn't affect my warranty. This is my 6th Harley over the last 23 years, I have never been more disappointed in the performance of my 2013 Ultra or the service department at my dealer that is an hour away. Let me know how you resolve the surging, at their cost per hour its hard to leave it with them to explore and another $400 to dyno it after $550 to put the race tuner on it seems crazy.