i was recomended ngk -9 plugs for my tune-up from serval different racers on some froums i go on;;;RBS has killer deal on -10 ngk's..what's everyones thoughts on going from -9's to 10's?or should i stay with the -9's?if i go to the -10's what changes think i'd need to do;;haven't made any passes on the -9's so don't have a plug reading;;i put my eng specs on the fourm's and -9's was what most suggested me to go with;;I need to buy plugs ASAP;was having plugs reached to me to reinstall in car and they dropped 2 of them on the floor so i'm affair to use them for test n tune..not sure if they got cracked when dropped and Iknow that would be bad news if cracked and try to run car with them so need to buy new plugs to be safe then sorry;;