This is an idea of Cary's (tube80z) that I've wanted to implement for a long time. Steve Parmley (zlalomz) has a similar set up in his red car. I wanted this to be lightweight so I used 1.625 x .065 tubing which is roughly 1lb per foot, and there are rougly 7' in there so figure about 7 lbs. This is attached to the roll bar tubing which is 1.75 x .120. I plan on using this same lightweight tubing for strut braces in the front as well.
I think this X brace is a really really good idea because it braces the strut tower to the strongest part of the cage, which is attached to the strongest part of the unibody.
I had to cut holes in the fenderwells to get the bottom of the tubes welded, so that is in the pictures. Took me quite a few hours to get all the tubes notched and ready to weld. I'm not very good at welding where tubes come together at shallow angles, so that part came out a little messy, although I know it's attached plenty good.
When I modded the control arms I was considering somehow attaching the control arm reinforcing plates in the last picture into this X structure somehow. I'm still not set on what to do there.
I need to get a bit more 1" square tube, and that will be welded into the top corner of the deck and notched to fit the top of the X.
Pics: