Fiberglass Thickness

I am making 2 custom boxes for my 2 10" subs.  I have a 1999 civic 4do and im makig them right behind the tail lights where I dont use that space anyways(iv worked out how to get to the tail lights if i need to get to it).

I am doin custom tweeter pods also. I used the following fiberglass from Bondo and their brand of fiberglass resin:

http://www.midwayautosupply.com/detailedproductdescription.asp?1285&affiliateid=froogle

Im wondering if that is 'thick enough' fiberglass for a subwoofer box.  I see that there are different densities and i dont know much about that.  The tweeter pods are going to turn out great. I just dont know if the subwoofer box would turn out great if I used that type of fiberglass also.  Any information would be helpful.

Oh also i saw that they have bondo fiberglass cloth that seems pretty think(like a carbon fiber weave).  what do you think of that also? thanks

Any density of matt is usually fine, if its thinner you just gotter apply more layers, if the matt is a thick varitey you can apply less but its harder to work with for detailed curves and such.  Thin stuff you would proberly be looking at up to 7 or 8 layers to be on the safe side.  I dont usually use cloth becuase i find matt is easier to apply, but cloth can give you a slightly smoother finish somtimes.