Ford's new Mustang platform is a vast improvement over the Fox body with chassis rigidity upgraded over 30%. While this is good news, it is still a uni-body and we are still left with a front and rear subframe that is not connected. BMR subframe connectors take over where the factory left off. Both tubular and boxed designs complete the frame by tying the rear control arm mounts and subframe assembly to the front subframe. The HD boxed subframes go a few steps further by triangulating key structural points together to make a very rigid frame.