We are kind of talking about the same thing but, I will agree to disagree with you. I don't care if you track the car or not, it flexes. Tracking the car makes it worse and that is why track cars are all welded up. I believe boxing any part of the car together has got to stiffen it up.
The whole chassis is basically a U channel and the only thing that completes the "box" is the roof and the pillars. The pillars are the tiniest things in the world. That being said, tying the strut and shock towers would help. I mean, only every track car built would be wrong, lol..
As I said, roll your window down, drive one wheel up on a curb and feel the chassis flex.