My 451 has Mahle plasma moly's on Iconn forged pistons. The gapping instructions that came with the rings had specific instructions for nitrous, supercharged, ect. Everything I remember with the literature that came with them seemed to suggest that they were fine for Nitrous Applications. Even though I don't have any immediate plans for a nitrous system, I gapped mine per the nitrous application, with the thought that I may someday throw a mild system at it.