Possible low voltage issue

[swervinmylac]

Alright so i finally got my system installed. As of now im running 4 15 inch woofers and 8 speakers for mids/highs. This is all in a 99 Suburban...

amps are: 4 total

x2 audiopipe 3000d amps (200A per amp)
soundqubed Q2-200 (80A)
precision power ppi bk520.4 (80A)

i also have an agm batt under the hood and two more agm batts in the back with a 180a/320a Singer alt. Big 3 done in 0 guage ofc but i have a single run of 0 gauge cca from font batt to back batts... The shop i went to put in a 200A isolator for the rear batts and the batts are not wired together. They each have there own 0 gauge run. Grounds are run to random bolts in the rear. Each batt is connected to one sub amp and one mids amp... It took about 8 hrs to install but man this thing SLAMS!!! We played it for a few mins at the shop about half tilt with no dimming or anything at idle... On the way home i happened to look at my trucks built in volt meter and it was reading under 12v. I turned the subs off and just played the highs all the way home which was a 40 min drive on the freeway because i figured the batts needed a charge. I checked voltage with a dmm when i got home and the alt was at 13.8v-14v with the stereo off and the front batt was at 12.4v.... Let it sit overnight and this morning i took a reading with the car off and i was at 12.8v on the front batt and the rear batts... Started the truck and voltage was at 12.7v on all 3 batts... Drove about 20 mins to warm up the truck and then took another reading with the radio on and truck idling, Voltage was at 12.5. The subs were on but the radio was turned down because i was in a business parking lot and didnt want to disturb... My question is does this seem ok with the batts never going into the 13s or 14s. By the way they are all duralast platinum agm batts... Havent had any dimming or anything yet but then again i have yet to play loudly for any extended period of time...

sorry for wall of text

Thank for all the help