I have the V&H Big shot true duals. Which are are one solid header/muffler from each cylinder on my 08. The real question is the sound that you would like to have. Listen to the different bikes with true duals. then get the one that sounds the best to you. IMHO
True duals, without any other changes, reduce the horsepower of the engine. You don't think that H-D has spent the money for crossover hardware on all models since 1979 for the fun of it, do you?