I plan to build a subwoofer for the home using a 15" Fi Q and Dayton SPA 1000 plate amp. My question is would two ports at half the length of one long port work the same in trying to reach a tuning frequency? Would I subtract the port volume from the total volume? Is the Fi Q a viable choice for a subwoofer? I guess that's more than one question. I have a large house to fill with sound and my current sub, a Bic F-12, doesn't quite satisfy. Thank you for any answers.