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I'm doing a trunk build myself in a 03 Civic sedan. Here's what I've found and it might be helpful to you. I'm running a single 15 on a 2k amp. Slot ported box. Current best is 145.8, so I'm not loud by any stretch of the imagination, but here's what's worked for me so far. Sub and port forward, sealing off the trunk, was the worst. Lost 3 full DB. Not .3, but THREE DB. Sub and port back was second worst, but I don't recall the exact loss. Sub/port forward with the box slid all the way back (furthest to the rear), was .3 lower than loudest. Sub up port rear, box slid half way back, was second loudest. .1 less than loudest. This is what I initially started with. Sub up port forward with the box all the way back was loudest.