building an enclosure

Ok I hope someone can help me or even perhaps give me the formula to figure out the optimal enclosure along with making it so it will fit in to my car. 2000 Mustang GT Convertible.

Here is what I have

2 Kicker 12in C XPL 2ohm subs

Here are the specs

Kicker recomends a 1.0-1.5 enclosure I would like to be as dead on as possible as to the size of the enclosure. Also What is the formula to find the Volume inside the box.

ok i have read through the "woofer enclosures" area and am still a bit cloudy on a lot of the areas ...

I read what all of the info means on the Theil Small however I don't understand how to translate that to what size enclosure i should have

Also what if my enclosure is not a box? what if I do something with fiberglass and is rounded ect... then how do i figure out volume. or better yet ... how would i build an enclosure using fiberglass to the proper size?

Check out this page, and then HERE is an interesting project to check out, HERE is also another place for some research.

Calculating the actual volume of a non-standard shaped enclosure requires some knowledge of geometry, but basically you look at the shape and find the squares, rectangles, triangles. cylindars  and spheres contained within it, calculate the individual volumes and add them up.  There is no easy formula for a non-standard shape, unfortunately.