Welcome to Just Commodores, a site specifically designed for all people who share the same passion as yourself.
Why do you keep starting threads when you've all ready asked the same questions, this is your 4th tonight.
Anyway it comes down to a few things,
>The sub itself, size regardless, a better quality sub will obviously sound better,
>Cone surface area, more area more noise basically,
>Size of the sub, typically larger subs will play lower fq's, assuming they are in adequetely tuned enclosures,
Just because it's loud, doesen't mean it will go deep, the lower the fq the more air your moving.