I ran an extra 3x2" RHS section across between the dash hoop and the door lock pillar. This is in the section where the sill is so adds a bit more side impact protection as well as tying the dash hoop and the door lock pillar together.
There are 2 2"x2" sections inside the door between the door hinge and the latch. But the hinges are a bit lightweight in my opinion and I plan to add a reinforcement plate in there.
The beam is foamed and glassed in which should stiffen things up too.
I sill wouldn't want to be involved in a side impact crash in a Cobra as I reckon it would be messy.
Cheers