most people dont even need two subs i have one and it gets twice as loud as my friends two diamond d3,s if you have the right box and tuned right one will scream just as loud as two or three
im 17 years old and still dont care to crank it up all the way when im just driving around there is basically no point when all you hear is bass unless your trying to impress the ladies then you crank it:D
ok well i dont fully understand all this stuff so if someone can just post a diagram of the best way to wire them up without destroying my sub thats what ill do