The sub box is made of heavy wall aluminum and is removable. Audio people often say this can't be done. We have done our re search to do this correctly there is more to it than just building an aluminum box. There are things that have to be done internally as well. We have not tried this specific box for sound but have done this before and if done correctly sounds equally as good as a MDF box and drastically drops the weight. Most importantly it keeps wood out of the car.
Dynamat Extreme and a top layer of 3M thinsulate will take care of that and still be a lot lighter than MDF.
Ah Mario, ya know I had a little left over from my build...What r friends for
Truth be told w/all the one off things you got going, that car of yours is going to be one incredible build, hopefully I'll get to see it finished at SEMA this year.