I would suggest either, or both. Battery is fast swap, usualy without any labor charges if you do it yourself. More Cranking amps will give you a little more overall listen time with the engine off, not to mention more overall power for cold starts and what not.

But a newer more powerful alternator can make all the difference. It keeps any battery topped off, so you don't ever notice power fluctuations.

If I had the extra dough, I would upgrade both.

 

thanks guys; im getting a new battery soon and i might as well get a better alternator