volts

I have a 97 civic with a pioneer deh-p8300ub head unit rockford r-750 amp and mtx thunder 404 amp when I got it all hooked up and my volt meter in I'm only getting 12.6 volts even when reved up any ideas why the battery is only a couple months old and even has grounds up graded to 4 gauge don't...

Hey everyone, I am not quite a noob to these things but no where near an expert, I am trying to learn about the really techy details of my system, so I can optimize the amp and speaker settings. I have 2-12 inch db drive subs that are 4 ohm, dual voice coil, 750watt rms a peice. I have them...