This option part makes the top deck and whole car very stiff in the axis direction of transmission and stiff at any serious crash, but makes the chassis with suspension flex when needed. By letting the chassis twist, the car can get more grip without making the suspension any softer (and increasing body roll). The car is more calm and is not so aggressive therefore it has feeling it is more easy to drive.
It is advised to make a small lexan guide that should be attached to the front shock tower to prevent the front belt from slipping down from the pulley in a crash.
The top deck is greatly forgiving on less than perfect adjustment of shocks, springs, if the car has the feeling of tweak or is not perfectly assembled.