Thats good to show how much you are pulling but not very accurate in telling you how much you're making.

 

True. However you get ball park of how much power you're pulling if you run your system at full and it is actually making what the manufacturer says it can make. I've never been to a competition to find out what my amps are making. Not that it matters. If your headlights are dimming, your headlights are dimming.

 

Theres your issue. You're using 8AWG wiring into your amps. You need AT LEAST 4AWG (and I mean true 4awg not stuff).

What fusing do you have on your 1/0 run to your distroblock?

 

I have the same issue:
Big 3 with 0awg. Voltage drops right down to 11.7v.
I already know the issue though...it's the crappy 4 gauge wire going from the battery to the amp. lol
I have to agree here, change that power wire, and make sure you at least get GOOD 4 gauge wire. There seriously IS a difference....big difference. I got some new 4awg wire and compared the two and the difference is insane.