For a Mach1...does anyone know if the motor is tuned for 87 or 93 octane? I use 93 premium, however if it's tuned for 87, it'll run better with regular 87 and im doing more bad than good....The manual says 87 but the manual doesnt specify model...its also for v6, gt, ect....does anyone know for sure if the Mach is tuned for 93??