Motorcycle Repair: ignition h.d., vance hines exhaust, market pipes

Question
QUESTION: hello mike. first i would like to thank you for your past responses.Heres my question, my ride is a 20001 flhtci with stage one h.d. from dealer and Vance hines exhaust.I'm getting more and more popping from the pipes when letting off the throttle on down grades. If I row the throttle slightly that gets eliminated. I've sprayed carb cleaner around the intakes with no increase in rpm', my exhaust clamps are tight,spark plugs are excellent color and uniform, changed ignition wires, tested coil, what do you think is up?

ANSWER: Has it always done this or is this somthing new?
Mike

---------- FOLLOW-UP ----------

QUESTION: mike,when i bought the motorcycle the h.d. dealer said it's normal with after market pipes.  that seems reasonible to me but not to this extent. some days it's worst then others. can altitude or humidity have anything to do with it? would it be my valves?

Answer
What is happening is when you shut the throttle off fuel is still being put in the throttle body. the ECM is not reacting fast enough. The ECM on the bike probably has not been remapped for the exhaust, so that is with needs to be done
Good luck and happy riding
Mike