Why you don't need a capacitor - Realm of Excursionits a big read but there is alot of info there,
and caps ****, a cap will discharge quick but it takes a much longer time to charge back up than most people think... plus the bigger the cap the longer it takes to charge and discharge. and it will NEVER reach its full charge, just how caps are. a good car audio batt will discharge as fast (some are faster) than a cap. and you WILL see a initial voltage drop.
now if i drop to 14.1 with my proper electrical why would i ever want to put a voltage drop into my system to keep the headlights from dimming???
op do it right get a good batt for up front and a h/o alt and you will be very happy. also keep in mind that a system is only good as its weakest link, so that means you NEED a proper ground in back (or do a negative run up front to the batt terminal), and a way for your alt to charge, so do your big 3
and p.s. i have witnessed a drop from 14.6v system off to 13.7 system off with a cap installed, and it was noticably quieter.