If you're limited on space I would highly suggest you go with a single 15" ported instead of trying to squeeze two 15's in small sealed enclosure's.

Look for a 15" driver that will give good SQ and have brutal output with the ability to take the power of that amp.
DD9500 and the new RE XXX are two that come to mind. XXX will look sick inverted if you want to save space and get that "show" look at the same time.

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