As we currently understand physics, the speed of light itself cannot be increased beyond the known 186,000 miles per second limit. Light can be slowed almost to a stop, but nobody has demonstrated speeds beyond 'c'.
The information in a light wavefront can be accelerated beyond the actual speed of light based on several experiments over the past decade. One experiment done several years ago involved firing a laser through a Cesium filled chamber. The excitation of the Cesium atoms caused the wavefront to be emitted to a point beyond the chamber at an apparent speed of 310c. You can read about it at:
Recognize that none of the experiments you will find show any change in the maximum speed of light - they only demonstrate that effects can be measured that appear to move faster than the originating wavefront. Einstien's theory regarding light speed has not be disproven.