IIRC, on unibody Mopars the actual rocker panels are stressed members of the chassis(note where the LATERAL boxing of the rear subframe is on a Hemi car.) The rockers are not tube steel, but they are rolled, double wall steel which are quite strong unless compromised by a significant side load. If this were not the case, a Mopar would collapse like a beer can if it were hit in the side, no?

Therefore, it is logical that on a unibody the further out you reinforce the perimeter, the more effect you will have on minimizing the torsional, or twisting motion. I suggest that with regard to torsional strength, thinner tubing further out from the center can be more effective than larger tubing closer in. The closer to the center, the less effective it will be. Beaming rigidity and compression forces (certainly the main considerations in a rigid foundation in terms of a roll cage) benefit the mostfrom subframe connectors, torsional rigidity is enhanced with a roll cage primarily through the cross bracing BETWEEN the subframe connectors.

A unibody is just that, it's more likened to a monocoque design. That means the roof and floorpan are also major contributors to the strength. A good basic understanding of these can be found in Herb Adam's 'Chassis Engineering' book.

Roll cage issues aside, I've often reasoned that long-Double heim joint adjustable bars (with anchors welded to the subframes) could be lighter and more effective (by being able to adjust preload side to side) than standard subframe connectors. Never got drunk enough to try it though

Wize