If you are peaking at 100-125 amps, the voltage of a pack rated for 100amps will drop = less speed.

If you get a 30c or higher rated 3s5000mah pack, you'll get 150a continuous and the batt will hold it's voltage better. Take a look at the hyperion35c thread on this forum. At 20c these packs hold 3.7v per cell.

Use the speedcalc and see how voltage drop affects your speed.