Question: what the difference between dual 2 ohm and dual 4 ohm?
Answer: It'll also determine the amount of power the sub will demand from the car amplifier or head unit. Basically, a 2 ohm subwoofer demands less power from the amp and tends to deliver louder bass. On the contrary, a 4 ohm subwoofer will demand more power from the amp and deliver less loud but higher quality bass.