Light weight enclosure material?

I am planning an enclosure for 2 JL 10w1-8 subs to go in my 95' Mirage.Needless to say every pound counts.While the dense make up of MDF is perfect for enclosures,it wieghs far to much.I was considering using birch or some other hard wood to construct it.I have used .75" birch before for a single 15" sub and while it was light,it did tend to resonate at certain frequencies....not cool at all.If any one has any suggestions on an alternative material or methods of dampening that dont add too much wieght i would greatly appreciate it.

best regards,

Scott

First , MDF wieghs more than fibreglass when the box is done, unless the glass was done by a total noob. if youre gonna do track forget the subbox...that not how its done. Instead of an mdf box with subs that will kill your suspension over time you put 6inch midbass drivers inthe doors and youre good.

even a carbon fibre box is still gonna weigh too much to be practical- forget an off-track soundsystem thing- instead build smaller enclosures or as few as possible-

I built up a 4x4 jeep to offroad and the guy put 6 of the orion 6inchers flush with the backseat- man that thing CRANKED- no roof on the jeep meant you could hear it before it even got into the city

the point is that for the 2600 wRMS he had the total install weight was minimal.it was a tiny fibreglass box i think .2 cubic feet per driver as per LEAP and the ORION spec.

but big driver=big footprint so youre not gonna reach your goals building ANY sub boxes other than tiny fibreglass ones

look for 6inch high end drivers and half ohm stable amps- once you see what Im getting at youll see the possibilities for lowering total wieght and still twisting some heavy decibal.

Hope

Thanks for the replies guys.This is obviously my daily driver,i only get to run it on track twice a month at the most.That being said i can deal with a little added wieght in day to day driving,so long as i can pull it right out come track time.I have allready finished the amp rack wich is completely removable,made from .5 in birch and upholstered with vinyl wieghs in at 8lbs(without the amp,soundstream reference 405).Since i only plan on using a pair of JL 10w1v2's in a vented enclosure i dont think i will be needing a very heavily braced or reinforced design,certainly not heavy enough to ruin my springs.So far my plan is to use .75" birch and paint the entire thing with resin,no matt just resin.I will add an extra .25" panel to the baffle and will brace the baffle to the rear with wooden dowels.I had considered usin a pair of 8" woofers in the side panels in the back instead.The dampening required behind those panels however was one reason i decided not to,the money for supplies i would need to make them look good and still be removable was another.With the idea i have now it will be a cheap build and will still be completely removable,not to mention should sound pretty damn good.I would like to hear from anyone else that has designed a setup with these same  limitations.                                                                                                                

that is the most rediculous thig ive heard- -JUST a par of JLs??? youre kidding right?