Are you looking for mods? Or is your question about the engine/transmission in stock form?
I have been looking for some mods as well. I figure there are enough parts for this engine considering the number of products it is in...especially the Fusion and Mazda3. I know Steeda makes a CAI kit for the Fusion 2.5L worth an 8 to 10 hp boost and a claimed boost in fuel econ. No retune necessary.
I would like to do a CAI, cat-back exhaust (magnaflow possibly), and retune the computer. I'd like to see about a 10 to 15 hp boost without a fuel economy penalty.
In stock form, I am pretty happy. I have enough hp to get up and get around some idiot on the freeway and do not worry about freeway entrance ramps. Around town, I drive with fuel economy in mind, so I accelerate fairly leisurely...though it will scoot when you goose the throttle.