Pre-heat oven to 325 degrees F (165 degrees C). Grease and flour a 9 or 10 inch tube cake pan.
In a large bowl, combine cake mix and sugar. Make a well in the center, and pour in oil, sour cream, eggs and lemon extract. Beat on low speed until blended. Scrape bowl, and beat 4 minutes on medium speed. Pour batter into prepared pan.
Bake 40-45 minutes, or until cake when tested with a toothpick comes out clean. Cool in pan 15 minutes. Flip out and finish cooling on rack. Store in covered container.