at the time the amp was 289$ the subs where 250$ each, thats all i can find for links, and the rule of thumb for caps is 1k watts = 1 frad, so yeah,, but i never was a fan of cap's as the local car audio said to get one,, wast of money in my view but owell Information About Capacitors - CarAudioForum.comYou're doing something wrong...maybe your capacitor is too small or not working properly. Why don't you just do yourself a favor and go down to a good car audio shop and show them what you have and what you may still need to do. My son's system was that big, probably better and spent way more than you did, especially in speakers. And the system ran fine with a 120 amp alt.
Further, you amp rating is highly exaggerated in car audio. That would be 1200 watts RMS total, not per channel and that would be peak-not steady through 20Hz-20KHz.
as for my amp comes highly recommended in the car audio world
"Big 3" did all but alt cuz i couldnt find a good one lol http://www.caraudioforum.com/showthread.php?t=352271