Well, both Optima batteries for cars have 800CCA, so that's way more than stock. IIRC, the Yellow Top has ~8hours reserve on it, so you can run the accesories without the motor for a good while. I've got a Red Top under my hood, for now anyway. Ideally, I will have a Red Top for the engine/starter, a Yellow Top for the stereo, and a cap for the sub amp at least.
Besides, it just looks better!!