I'm constructing a box for a Treo 18" SSX sub. The box is 5 cubic feet and being tuned to 35 Hz with 50 in^2 of port area. I was wondering if I use 10 round ports (3" Diameter by 5" length), will I have a lot of port noise and will the sub sound bad b/c i've never used round ports before. Or do you recommend I use a slotted port?? Thanks.