Guys, I'm sure you're sick of seeing these questions, but I'm sick of seeing so many different answers with using search/google. I got a great deal on an Optima Yellowtop 4378DT. It was $50 from a friend. She had it in a ride, with a small system, for about a month before selling the car. It's brand new(still had the little coupon book taped to the side, lol), and I couldn't pass it up. It doesn't fit under my hood, but there's a brand new battery there anyway(w/550 CCA, 685CA, and 80 reserve minutes, don't know the AH). So, it's going in the trunk. Do I really need an isolator? I planned on running my power wire (4 gauge knu kollosus fleks) to the Optima, and then running a little bit more of the knu(still have six feet left from install) from the 2nd battery to the amp. I also planned on grounding the battery to the shock tower (metal already prepped as that is the current amp ground), and then grounding the amps to the battery -. I have a stock 105 amp alternator, and my amps are an Audiopipe APSM-1500 (running at 2 ohms) and an Eclipse 3640. Thanks!