Thank you very much for your replies. It's much appreciated. Based on your comments, I'll be using 1.5cu.ft. per sub; that'll make me fall in the middle of the SQ vs SPL volumes specified by PG and won't be an issue if PG crossed the values in their spec. I'll split the enclosure in two sepatated se...

Ok good for the size. What about the poly filling and partition inside the box?

I have a pair of 15" Phoenix Gold Titanium Ti15D (each with 2x 4ohm) I bought new back in 2003. I'll feed them with a the pair of R500X1D Rockford Prime amps. I want to install them in a sealed enclosure. My main question is what volume does my enclosure needs to be? How does polyester filling ...