That looks like it is for the front somewheres.

 

That's a Nismo power brace, used to stiffen the area in front of the crossmember.

Hey craig, where are you going to plug in that sawzall? I do think that this would increase chassis stiffness, but only if you didn't already have a cage. A cage is so much more structurally sound than this kind of bracing, because it can resist z-axis forces (that's up and down) more effectively.

Then again, you won't crack your skull open on this in a fender bender.