Also, don't forget, slip ons on a crossover system can really help. Still keep the basic look of a true dual, but get a little of the backpressure the 2 into 1 provides. I have a true dual, but if I had to go back, I would have possibly gone that route.
I never really liked the look of the 2-1 pipes on the new bikes in 2010. Then I decided to try a Vance & Hines Pro Pipe as it was touted as a good performing and resonably priced pipe. I bit the bullet and love the look, particularly that nice looking megaphone muffler. I've now changed my mind in this regard. I think the look of one verses the other, depends on the styling of the system. The Pro Pipe in a 2-1 is sweet looking by design, and performs better than I expected. Sound is also just about perfect. Nice and throaty while cruising but snap the trottle open and you can make it Bark!