[monkeybutt]

Quote:
"...I intend to mount the second one in the boot. But my concern is any lack of documentation with the subwoofer, thus not allowing me to have an idea about the exact specs & dimensions of the enclosure it needs."

You probably have these T/S parameters.
::  i l l u s i o n   a u d i o  ::
If you are concerned about the exact measurements for your particular driver, unless you are doing ported and the factory specs are way off you should be okay for modeling.

I believe you were interested in isobaric so: Sealed Subwoofer Box Design Calculator

 

[monkeybutt]

Depends if you like the sound of your sub as is, then '1' should be okay. However, when I run 2 of your subs for isobaric through the calculator I get
.95 cuft w/ a Qtc of .7.
Again, not sure of the perfromace gain going isobaric, but box size reduction is apparent at the expense of complexity and depth of box.