If you're getting cold feet, now is the time to turn back. After you make your cuts, you're committed. Begin your preparation for cutting by etching a line into the plastic of the mud flap. I chose to make my cut right below the point where the plastic curves downwards. As you can see in the picture, the cut will fall right below the point where the rear reflector mounted. These holes will be used later to mount the license plate. In order to make the cut I used a Dremel-type rotary tool with a fine cutting wheel and low speed.  You can see the beginning of the cut in the picture on the right. Take your time. Stop and check your progress often and remember that this is the only part of the job that cannot be easily undone. Be sure to use some sort of eye protection.

Don't worry too much about small inconsistencies in your cuts. After cutting is complete, you can use a deburring tool and a file to clean up the edges.

After your cuts are complete and you have removed the mud flap, slowly clean up the edges of the cuts. If you have a deburring tool, use it but go slowly. Otherwise, use a medium file or rasp working the outer edge until its round and smooth. Using this method, I was able to get an edge that appears to be factory until you get within inches.

Finally, reattach the charcoal canister with the zip ties from Radio Shack.