I still think it boils down to what "rings our bell" as far as looks and sound, right?
Friend I met here yesterday has a one-off FatCat based system on his custom bagger, looks and sounds pretty nice! Too loud for me, but, he is younger anyway!
I have true duals on my hot rod and it's too loud for long distance, my new bike has the full Fullsac treatment, and after this last trip and 6000 miles so far, it sounds like music to my ears! Long days in the saddle are NO problem. No, I don't wear ear plugs~!
I like the "stealth" look on the new bike, stock looking mufflers, head pipe, air cleaner cover, etc.
I have seen personally on my bike what each upgrade has done to my dyno numbers, can't say anything is skewed, watched as we made changes all along, I'm convinced that what I have works for me, but, I still like to play with my TTS just a bit! LOL
Put on what you like, but, do your homework first and you won't be wasting money!
JMHO

Consider these - they have proven dyno results ! : 
Details
2010-2011 Harley-Davidson FLH / FLT Bagger motorcycles: D&D 2 into 1 Boss Fat Cat Exhaust pipe.
PIPE OPTIONS
- Black Pipes
* 556-31B - With back cut tip
* 556-31L - With slant cut tip
- Chrome Pipes
* 556-32B - With back cut tip
* 556-32L - With slant cut tip
Note: (Slant cut works with the CVO Extended bag models)