Added a rear brace that goes in the trunk and ties the shock towers together. I am sure it adds to the overall stiffness of the car, but I can't tell any difference. (Unlike adding the H-Brace, which was noticeable) The last step will be to add the front brace.

 

When I added the rear lower brace and the toms 6 piece it made a huge difference of just pulling it all together. I would highly recommend these 2 as well.

 

The rear bar is really useless, but I added mine anyways cause it gave me something to do.

 

its not useless. it actually does stuff. but most GS's are not pushed to the point where it'd be absolutely necessary.