Airfoil Modification
Reducing the arc on the bottom of a symmetrical airfoil (no mean line camber) changes it to an airfoil with mean line camber. The devil is in the details. If too much of the bottom arc is taken off, the drag will increase in high speed flight. The thinning of the airfoil will reduce its minimum drag but it will occur at a lower speed. The increase in mean line camber will allow more lift in high speed turns and allow quicker, sharper turns. The balance between speed lost or gained in the straightaway and quicker turns will determine if lap times improve and by how much.
Why not go to an airfoil specifically designed for pylon racing like the S8052?