there is another thread similar too this already started, I know from Experience the yellow top doesn't make a HUGE difference, I had one installed, took it out and ran my stock battery with my "big3" done and I have no issues, and im running a T31000D and 4 10" subs

..I Hardly ever listen to it quietly BTW...
And as for the Altenator, I would just get it Rewound, they usually increase significantly and it doesn't cost an arm and a leg