Can help you here guys.....A cap will benefit any system, as long as it not a sh*t cap from maplins.!!!
A good cap will discharge and charge itself very very quickly, where as a cheap cap wont, and will become a resistance to the power flowing through it. Sarahs caliber cap is a good one so its helped her system, and Dink16v yours couldve been a cheaper one which is why it didnt seem to do the job....
I would always put a cap into a system, cos not only does it stop your headlights and dashlights dimming but it also gives you a better mid range quality of music.. Hope this helps !!