Adding fresh lemon juice and zest makes all the difference.
One Lemon Cake Mix (515g) I use duncan hines
One 4-serving size instant lemon pudding mix
1 cup water
1/2 cup vegetable oil
4 tablespoons poppy seeds
Juice and zest of 1 lemon
Preheat oven to 350 degrees. Spray with non-stick spray a Bundt or angel food cake pan. Combine dry cake mix and dry pudding mix in mixer. Add eggs, water and oil and mix until well blended. Stir in poppy seeds, lemon zest and juice. Pour mix into Bundt pan. Bake for 45 minutes at 350 degrees F. If top of cake looks wet after that time, turn oven off and let it bake a few more minutes. Remove cake from oven and let it cool at room temperature for 15-20 minutes, then invert into serving plate.
When completely cool, sift powdered sugar over the top, OR make a simple glaze of powdered sugar and lemon juice and let it dribble over the cake.