The problem you're still dealing with is the fact that the alternator really isn't up to the job of keeping up with the draw that a big stereo creates. An extra battery takes some of the stress directly off of the alternator for a while, but take a good long drive with the stereo bumping and eventually the alternator won't be able to keep up and you'll either burn it out or drain the system.

Erik P.
Official 2GNT thread Hijacker
Some say that he's driven over more Covenant than he's shot, and that his grenades aren't where you'd expect them to be...
All we know is, He's not The Stig... But he is The Stig's Spartan cousin!