Subwoofer Enclosure Vented or Sealed?

I have two JlL W3s in a sealed enclosure my amp is a Memphis Pr.16 something like that its 1000 watts at 1ohm so im pushing the hell out of em. i want it to sound louder should i make a vent and if so how can i do that i hav no expeirence can som1 giv me advice or somethin.