no,capacitors are more for bling factor these days.
you should be fine if you upgrade your earth cable from your battery to atleast the same guage as the power wire you run to your amps,and use that guage for the earth for your amps too.
if you have problems because you are drawing to much current before your cars system can recharge back to the voltage it needs,i recommend you upgrade your battery to an odyssey deep cycle or something like that...these have a faster rate of discharge and recharge