What would be a good subwoofer match-up to my 2500.1? I want it to hit!

Or maybe ditch the 3 subs and go with 2? one? I am open to any ideas. I just want the hardest hit out of my 2500.1

They are wired in series parallel. It's like they aren't getting enough power.
3 - 12" Dual 4ohm

I am brand new on here, and have limited experience in car audio (the technical stuff). I currently have a 2003 Acura TL-S with: 1 - Blue top Optima up front 1 - Pioneer DEH-P7900BT 1 - SHURiKEN - SK-BT20 in the back 3 - 12" Phoenix Gold RSdC124 - in a custom sealed box. All one chamber and app...