To each his own, but if it were me, I'd stay away from the true duals and go with a 2-1-2, or even a 2-1.
With those mods, I think you're gonna need a tuner. I did the same mods you are looking at using a Fuel Moto 2-1-2 & a Fuel Moto air cleaner. I used a Powervision and flashed the proper tune into mine, which was installed by Fuel Moto at the time of purchase, followed by a few auto tune sessions.
Either way, if you choose an add on tuner or a flash tuner, you're probably going to need to purchase some type of tuner to make the bike run right, and so you don't destroy the engine by running it too lean.
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2015 Denim Black RG, FM ss ceramic coated 2-1-2 pipe, White Bros Original E Series Mufflers, FM ac, PV Tuner