capacitor or no capacitor

[manguybro]

not sure if this is the right area to post this in but here goes...

setup:
85 s10 xcab with 4 12" custom box. 3/4+ cubic foot per sub
-140amp alternator
-4 gauge from battery back to a kinetik 2000 with solenoid separating front and rear battery
-2 to 3 layers of generic sound deadening lining the cab, interior was gutted during frame off restoration
-4 fosgate p2d212" subs running to 1ohm at amp
-critical mass ula2500 v2
-amlumapro 5 farad cap between sub amp and kinetik

is the cap helping or hurting the system? my thought was that it would help during huge bass notes. my local shop tells me that the newer amps (old school guy myself) don't need caps and that the kinetik is more than enough.

with the above setup, i still get lights dimming while parked and truck running. i know my grounds are good at both batteries, ive tested them.

so, keep the cap or remove it? battery strain tips?

thanks in advance!