There are plenty of "30C" packs out there that have similar internal resistance to those with "80C" ratings, and will therefore hold voltage as well and deliver the same amount of current. I use quotes because these rating are often complete bs, especially in the car world, where ratings of 100C or more are commonplace. In reality, few batteries can handle 30C continuously, but even relatively low C packs can handle bursts of 100C. Long story short, a good 30C pack will give you more power than you can put to the ground.