Do I need a new alt. or just a deep cycle battery for my car audio system?

I drive a 1996 Olds. Bravada. The battery is in the last few months of its 5 year life (going by the date on the battery). I recently installed a JL 13w7 and a JL 1000/1 amp. This setup makes my voltage meter in my dash jump around like crazy. I cannot turn the sub volume and the radio volume too high or it voltage... show more I drive a 1996 Olds. Bravada. The battery is in the last few months of its 5 year life (going by the date on the battery). I recently installed a JL 13w7 and a JL 1000/1 amp. This setup makes my voltage meter in my dash jump around like crazy. I cannot turn the sub volume and the radio volume too high or it voltage needle will sink down near the red and cause the radio to shut off. The amps input level is only about 1/4 of the way up. I have the sub volume set now where I can play it and not have it shut off. The voltage needle still drops kinda low when deep bass hits though. It still pounds but obviously not as loud as it could. For this system, do you think I could just add an optima battery and upgrade the big 3 or would I probably need a bigger alt? If I had the money I would simply upgrade everything. Please let me know what you think. Im not an electrical genius so thank you in advance for the answers.
7 answers 7