Basically I was using a tube of expanding foam the other day and that's when this wacky thought occurred to me regarding filling all the following with the stuff
A & B pillars
Front & rear cross members
You could inject it into every chassis point throughout the vehicle but prior to injecting it I would spray some kind of light oil into cavities in order to water seal them.
It's light and very strong when cured and it surely has got to help with the overall structure of the chassis and if done correctly will help stop rust forming too
Probably cost around £20 to do entire car so will see how it turns out and how it helps on track as il not be using a cage