I took my car into a local exhaust shop. Guy made a custom cat-back exhaust for me using 2.5-inch stainless steel pipe, deleted both resonators, and used Magnaflow Mufflers. Cost was much lower than existing kits from Magnaflow or Borla. In addition, since this was a custom fabricated job, all pipe work was welded as opposed to pressure bolt connections on available kits online. I recommend this route over purchasing an online kit.
As for lowering springs, I recommend the Tein H-Tech or Tein S-Tech (both available for V6 models). S-Tech's have a 2.1" front drop and 1.6" rear. H-Tech's have a 1.5" front drop and 1.0" rear. Fusions tend to sit a bit rear heavy so the extra drop in the front provided by these springs allow for an even overall drop. Both springs are great, just a matter of preference on amount you would like the car dropped.