Technically, that part is called the "Tunnel Reinforcement" bracket in all
the Chrysler/Dodge Factory Service Manuals for the 300/Magnum.
Its there to aid in stiffening up the tunnel where the exhaust, and most
importantly, the driveshaft goes.
You can take it out, but you can possibly loose some structural stiffness
as it was put there to help with some of the stresses from under the car in
Some people have noticed no difference in the ride/handling of the car when
it was removed, and some say the car makes more sqeeking and groaning
type noises after it was removed, and put it back in.