Nice idea!! I went and bought an MTX enclosure that fits under the 60 bench and while it looks great and you'd never know it was there, you cant fold the seat down much past half, which kinda sucks. You might be onto something there with that idea of removing the 60 bench and swapping in a 40 with the sub box in the middle. What are you doing with the top of the box? It would make a nice place for some built-in cupholders and a maybe a small rectangular indent on to place stuff.
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