It will help your car but you probably wont be able to notice it. The only way you will be able to notice a difference is if you go the whole nine yards. By that I mean, upgraded sway bars, new bushings..etc the list goes on forever.
It works by elimanating chassis flex by tieing the two shock towers together. This makes the chassis more stiff and rigid, allowing for better handling..etc.
<img src='http://img127.imageshack.us/img127/4284/bmwlogo2new17jy.jpg' border='0' alt='user posted image' />
Black 4 door 1990 325i
15"x7.5 Ronal LS-wrapped in 205/50-15 Bridgestone Potenza G009