National Shot Peening NSPI was purchased in 1992 to continue shot peen forming of the Gulfstream G4 executive jet’s one piece upper wing skins and Boeing’s 747 lower wing skins along with saturation … NSPI was purchased in 1992 to continue shot peen forming of the Gulfstream G4 executive jet’s one piece upper wing skins and Boeing’s 747 lower wing skins along with saturation …