i am not sure what you mean by port noise, but one thing to check: make sure the sub is not receiving signals below the box's tuning frequency, this will cause the box to "unload"
changing the port size or length will change the tuning frequency, you will have to chakc with an enclosure design program about making these changes
KC
changing the port size or length will change the tuning frequency, you will have to chakc with an enclosure design program about making these changes
KC