I have been reading that Ford updated the spark plugs for the 13 model year SHO's. The newer part number is a Motorcraft SP534 pregapped at .030. I was curious being that my car was an early 13 build. Car just turned 8000 miles. Unfortunately, the gaps where all over the place from .032 to .038 so I'm glad I checked and replaced. In addition, the plugs were not the newer SP534's.
Overall not a horrible job, but the rear closest to driver side is a major PITA. Took me about 1.5 hours for the plugs and tightening some of the cold and hot pipes which where fairly untight. Check your clamps guys and gals as they back off over time.