winkychevelle 10+ year member
CarAudio.com Veteran
no one can just tell you this setup will be louder than that setup with out lying. being loud depends on too many variables for some to say yes this or that is louder. but that being said if you go from one 12 on 1000watts to two 12s on 1000watts in a pair of the same boxes you had before you will gain 3db same as just doubling the power to 2000watts on the same single twelve. so double power or double cone area and you gain 3 decibels. but thats in a controlled environment sound room not a car. cars have even more variables that make it even harder to say this or that without actual testing first