I've replaced all of the bushings on the car with PU from ES. It made the car fell very "solid." I also have the DTSS but I would assume that the results would be similar without them. I recommend this mod to anyone who is willing to do it themselves.

Bracing the rear control arms looks to be impossible. You could maybe use larger diameter trailing links or even fabricate some sort of spherical heim joints. I believe the problem is that the rear control arms are bolted onto a moving subframe and not directly to the frame of the car. So no matter how much you brace the control arms the movement in the subframe will still be present.

 

Jimmy - You may have to adjust your tire pressure.
Mine handled really loose until I dropped the tires to 26PSI.