why dont you guys use birch ply, its much better to work with and so much lighter.
If you know what your doing and have the right products its so easy to have great sub stage. DC audio, Sundown audio both released CRAZY 8 inch subs that will most likely keep up with most 12s without a doubt and take 1000wrms with ease. There are also other companies for you guys that love the shallow mounted subs that you can do the same with. Another little tip, The rear bench backrest can actually be moved forward utilizing only one bolt instead of 2 and a spacer template used for the bottom to extend it forward by 2 inches to allow the seat bench bottom to still move up. This allows for much more room in behind the seat!