pyle subs need a box size

hi i just purchased a pair of pyle plm1599d  dvc subs http://www.pyleaudio.com/itemdetail.asp?model=PLM1599D  <-- is the pic at thier site.  the manual to these subs dont state what size of reccomended box the require. i want to make a sealed box for them for my car but dont know how much cu ft they require the max size i can fit for a box in my car is a 34x18x13.5 box that equals about 3.7 cu ft of air space inside for both subs and it will be partitioned so each sub has its own airspace (1.8 cu ft for each sub). what i want to know is if anyone has these subs or knows how much cu ft of airspace they require? i cant contact pyles support  says page cannot be found everytime. any help will greatly be appreciated. thank you

Your best bet would be to call Pyle http://www.pyleaudio.com/contacts.asp