What are you trying to achieve with 8 AWG that you can't with 12AWG right from the battery, if not using the internal amp in the HU.... If using an HU with a beefy DC to DC converter, and you want the most out of the HU for your speakers, then you will gain from running a 10 AWG wire directly from the battery, but 8 AWG is overkill... especially when you're not using the internal amp.

Mark

 

you dont need any bigger than 12 to the headunit. you put all grounds together to eliminate ground loops noise. you need to ground it in a very quiet spot. how do ou find out where this spot is. you use a ground sniffer.

always remember that your system is as good as the weakest link. so joining those grounds will allow current to move easily back to the battery. and not flow back thru a compenent and create a ground loop(noisy ******).

as far as the battery. just make sure that the one you have is ok. but the cap thing. id put before the distro block. front need a cap as much as bass. one cap seems pretty insignificant to your setup. i would take it out nd get a really good alternator. but that is my opinion(im an spl guy).

you will learn that you dont need certain things and really need others. it depends on whether or not you plan to listen to it
extremely loud all the time
moderate levels all the time
for small amounts at a time
for long periods at a time
with the car at low idle or parked
with the car at high speeds
with the car off
or any combination of these. each requires different amount of power from your electrical so you need to figure that out and plan for it. most extreme case is extremely loud with the car off(which kills amps, batts, alts, etc) which will start off as dimming lights.

good luck and keep us posted as to your progress.

 

biggest money making skeem in the known universe caps are bunk unless your running a sq comp car.

it is a known fact that a cap will not fire till the voltage gets below 10 volts