It will likely be achieved through software alone. That means much like the Competition Package for the F10 M5 S63TU they simply are giving you a bit more power with a warranty on the factory turbochargers.
Speaking of the Competition Package, what happens to the package for the M3 and M4? The $5000 package bumps the S55 to 444 horsepower but if the M3 and M4 have 450 horses standard what is the point? Does that mean another, new Competition Package? Will the next one offer more than just new software to achieve its rated output if it comes?
Once again, this is just rumor and speculation. What leads credence to this rumor is that the X3 M is on the way and if it uses the S55 motor as speculated it may get development revisions that then find their way into the F80 M3 and F82 M4.
It is also possible that an M3 CS and M4 CS launch with the Competition Package as standard which is what is leading to this rumor circulating.
We'll know soon enough.