It is obvious from the variety of responses that exhaust selection is a personal and subjective combination of appearance and sound. Most don't understand the magnitude of the effect the right exhaust can have on the power output of the H-D vtwin. I have seen a difference of 30 foot pounds of torque between to different systems. That is an extremed example but makes the point.
Much to be considered when evaluating exhaust changes in the late model. The first step would be the elimination of the cat converter in the head pipe. The cat can be "drilled" out; the pipe opened up and the cat removed or the head pipe can be replaced with an '09 catless or an after market head pipe. IMHO, one should consider replacing the restrivtive OEM exhaust as an opportunity to upgrade performance; there is a fair amount of power to be gained.
The newest after market approach to head pipes is the x-pipe; Fullsac and Fuel Moto probably have the best current offerings. I have seen dyno charts comparing the two with the exhaust change being the only change and the Fuel Moto pipe out performed the Fullsac pipe in that comparison; not by much but enough to convince me to select the Fuel Moto pipe. The V&H Power Dual head pipe is another good offering.
The mufflers are a matter of choice and the possiliites range from drilling the OEM muffler baffles to replacing the OEM baffles with aftermarket re-cored baffles like the Fullsac offerings or replacing the mufflers with offerings from Rinehart, Cycle Shack, Rush, Fuel Moto and Vance & Hines; there are others but those listed are better known.
One can mix head pipes and mufflers but, IMHO, it makes sense to match the head pipe with the mufflers. IAW, if running the V&H Power Dual head pipe, run a set of V&H mufflers, like the Monster Ovals, etc. A true x-pipe merge collector head pipe true dual system with the right mufflers can produce very similar numbers to those produced by a 2:1 system. The torque curve will vary a bit but the numbers should be very similar.
Of course the A/C should be opened up to complete the Stage I upgrade to maximize the performance benefit of the upgrade.
The other componenet often avoided because of the added cost is a good flash tuner and a dyno tune. The Dobeck Gen3/4 units are OK but not flash tuners; the best results will come from a flash tuner like the TTS Mastertune or the Power Vision. In the hands of a competent tuner that will spend 3-4 hours tuning the motor will greatly improve performance, rideabilty and often times fuel efficiency.
The total Stage I package should inclued a good free flowing exhaust system, a free flowing air filter, a flash tuner and a proper dyno tune. The combination of the right components and a good tune can produce amazing results in performance.