Power requirements for this setup?

If you wire 3 batteries in series to power your system, your shooting 36+ volts into your amps!  When connecting multiple batteries, wire them in parallel so voltage stays constant.  You probably meant in parallel, but I just wanted to make sure.  I'd hate to see anyone smoke their equipment.

the amps your going to be adding produce more power and are going to demand more from your alternator . then the ones your running to your subs . what type of vehicle is this going in ? and the thing with adding batterys ,and not an alternator. is that if your drawing more power than your alternator produces.what this will result in is the extra power stored in the batterys will be gone over time.

switching to the same subs is a good step in the right direction, keep the subs the same and put them in proper box's with deicent power running to them. throw in a deicent HO alternato and a couple batteries (depending on there ratings)  but keep in mind what you want it for when getting the batteries,  if you want to listen to the music for a long period of time or just quick loud burst's (like at a competition)  that will change the type of battery you use,  a regular car starting battery will be good for those quick burst's and a good deep cycle will keep you going for a longer period of time (someone correct me if i'm wrong here) just that's what i've always been told