Don't see how a increase in performance when you are taking out the resonators and installing the magna muffler and another borla pro xs at end and looking at another inbetween, would be more restrictive. Might be a loss in power.

If something is going to be happening anyway.
You have the magna flow now, take the resonators out as you want and install the dual in / out MagnaFlow then listen to the sound before you add any more (in building and with the short exhaust will be louder than finished out back) if to loud for you get a cheap set of resonator exhaust tips, and would tone down more.
And can do dual 2.25 back if you like the sound, be less restrictive, eliminates that sharp bend in pipe around rearend to the muffler.

Give us sound clips please on each stage.