Ive built an enclosure (2.4 cuft) and want to tune it to 35Hz with a round 3" port. Ive used a website that tells me i need to make it 4.28" in length. My question is that I'm using 2 alpine sws10d4's....would that mean I'd need to use 2 ports? Or, would one port that's 4.28" long give me the...