I beg to differ. Saleen and JDM engineering both require that plugs are one degree colder for the Saleen series VI 475 HP upgrade kit. And yet my boost levels don't exceed 7.5-8.0 psi with 39lb. injectors, 3.6" pulley and Autolite HT0 plugs gapped at .030" with only 7.5 psi and JDM 91 octane tune.
Perhaps VMP's test results claim that one degree colder plugs are only required when boost levels exceed 10.2 psi. However, when it comes to potential misfire issues related to engine detonation due to excessive heat, elevated cylinder pressure from running FI applications? there's obviously a very good reason the SC manufacturer recommends running one degree colder spark plugs. That being said, I haven't encountered any misfire related issues from running one degree colder spark plugs at all