x2... i didnt see any bracing, but it might just be hidden by the angle of the picsAli, did you brace between where the two subs mount? There isn't much material left there to maintain rigidity, I would have considered a brace right there, or as close as possible.
Can you possibly take a picture of the box without flash in a well lit area so we can see the way it looks to you? You know, without the flash affect?
Also, very nice box. The part about putting your name on it as a theft detterent made me laugh.