i have two X types, and the best way to do it, is to call alpine and ask them for spec, i have a cavalier and my hole trunk is a box!!! THE MORE SPACE OR CF. THE BETTER THATS WHAT THE ALPINE TECH GUY SAID.
that what i did and i have two of them and runing Two PDX-1.1000 for each sub and they are very very loud. ALREADY GOT TWO TICKETS FOR LOUD MUSIC AND STILL GOING STRONG!!!!!