That looks pretty significant to me.... at least from 11Hz up to about 25Hz.
Rodny... you gettin' all this. You need to go with the 10" ports...
No reason to do it halfway...
That Bradley Plumbing, IIRC, had a bunch of leftover pipe that they will probably let you have. Go to the back, not the front office and talk with the guys back there. They had all kinds of pipe in the yard. Or you might find some sonotube type stuff around Montgomery somewhere.