I second the alternator group buy. http://www.bonnevilleclub.com/forum/...ic.php?t=78333
With a high power stereo comes high current draw (assuming you listen to it loud most of the time-which is why you have it right?) You need an alternator that keeps up with this draw or else you will end up with dead batteries (if system pulls the all the alternator'* current and then some, the batteries drain too and the alternator can't supply enough current to the batteries and stereo)
Here'* some rough estimations for you. Together, your amps put out 2300w rms. For real music, they may be putting out 1/2 power on a regular basis. That'* 1150w output. At around 75% effiency together, they would be consuming 1438w to make that power. Since I=P/E, your amps would be drawing about 104A at 13.8v. That eats up basically all of the output of you OEM 105A alternator. You have nothing left for all the other accessories (cd player, abs, engine electronics, blower motor, etc) and for recharging the battery(*). Any current they demand would be supplied from your batteries. And with 2 batteries, that means one more load on the system demanding power. If you use your system to burp sine waves for spl competitions, you current demand almost doubles. So unless you want to periodically let the car idle without the stereo on, I'd implant a new alternator.