They are very easy to remove and replace with the clears. Even I did mine!
To remove, just grip the edge of the side marker that is closest to the inside of the wheel well, and pull out and pivot towards the front of the car. Disconnect and then re-connect the clear marker, put on that little black rubber grommet/doohickey. Now work in reverse, set the edge closest to the front of the car, and push the marker into place.
Takes about 2 minutes per side and increases HP by about 3.5 total!!