7. This photo also reveals that our intake valves were contacting the pocket of the old piston. We showed the contact area to CP and the company used this info to determine how much larger and deeper the pocket in the new piston should be. You'll also notice that the top of the pocket is not perfectly flat. The material at the outer edge of the piston is thin here and under the extreme heat of a nitrous hit, this material could become a hot spot and melt away, causing engine damage. CP puts a radius cut on top of the pocket, eliminating the thinnest portion of it to avoid this potential damage.