I haven't heard of any MS6 owner swapping out their body components yet.
But, regardless, the MS6 body parts aren't a straight swap onto the 03-05 Mazda6. So don't think you can just buy the pieces someone else doesn't need and just throw them on your car.
It will require a fair bit of work on the front end. Outside of the body parts themselves, you'll need a new radiator support, new hood latching equipment, and entirely new fenders to start. Those parts will all require some tweaking to get all lined up correctly.
Then, on top of all the body components you'll need them all painted because the MS6 red isn't the same as your red. And, since you're doing so much of the body you'll need extensive blending work into the rest of your car otherwise it'll look like crap.
You're looking at about $5,000 for all the parts, wholesale, shipped to you. Plus probably $1500-$2500 to install and paint at a reputable shop.