I was watching some Japanese tuner videos other an heard about a pretty intresting technique. Since most Japanese sportscars are hollow frame they injected liquid foam urthane into the structure of the car. It enters the body, fills then expands when it hits air and lasty harderens as tight as a rock in the body. Cheap and very effective more so then a roll cage supposedly. I might give it a shot on my FD.
Imput & Other Techniques...
(List only uncommon no strut-bars etc)