Actually, the boost in this image was accomplished by applying a Curve adjustment to the a and b channels individually. Simply move the endpoints of the curve to decrease the steepnes of the angle ( unless you have the sidebars reversed ).
Two caveats:
1) The curve must pass through the centerpoint of the grid, or you will introduce a colorcast to the image. So, either adjust both ends by the same amount or place an anchorpoint in the center of the grid before proceding.
2) Remove any colorcast in the image before applying the Curves adjustment, or the adjustment will amplify the cast.

-Joe U.