Cut off your left leg right at the hip. This will reduce braking and thus increase your speed upon turn in. It will reduce your weight by approximately 15% and thus improve your chances to compete. I found it very important to re-scale the kart as the balance will be significantly off.
Alternatively, you can cut off the right leg and simply pin the gas pedal on permanently. This is a little better for kart balance as the engine is on the right side.