So it's been a few weeks since I picked a new Interstate battery (following many of your suggestions). Had something like 150 cc amps left.
Since the install, I've noticed that without changing any of my audio settings as well as listening to the same music via the same formats, the low frequency levels are drastically increased. I'm assuming this is due to the increased amount of voltage being supplied to my amps, but I didn't really anticipate such an increase. So much so that I believe I'll need to make some adjustments on the amp levels as my Eclipse CD5435 has the bass set at the lowest setting. Can't imagine what it'd be like if I had a better sub than my single 12w6v2.
Just wanted to say thanks for all the suggestions.