Box build for 4 DC Audio 18 xl's

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Looking for some ideas on building a box for 4 18 xl's. They will be powered by a dc 9kw @ 1 ohm. I would like to be able to use the box daily and possibly compete with it. Info im looking for is tuning and port design. My max with is 48" its going in the back of a 01 suburban with 3rd row removed. I've built a box for my kickers here http://www.stevemeadedesigns.com/board/topic/181440-need-a-little-help-with-a-box-for-2-15-kicker-l3s/ but this build is on a whole new level. Any info would be appreciated.

Thanks

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Admin please delete. It posted multiple times and I cant delete them. Thanks