I read somwhere that if I were to put a HO alt in my car, it wouldnt do much unless I got a new battery. I assume hey ment a deep cycle battery. but is this true? or could i use my stock battery? Also, if I bought a HO alt to install myself, is there any brackets or extra parts needed, or is it as simple as pulling the old one, and putting the new one in and hooking up a couple of wires?
you don't need a new battery, but it never hurts to get a high CCA starter battery and/or a deep cycle depending on how you generally use the system.
the battery should be replaced if your stock alternator was damaged before it was replaced, since often times the battery gets damaged as well in such instances.