Alright, im building my first box, and got all the measurements and think it should go pretty easy since my dad is good at all that handyman stuff. I know how to use the calculator to get the tuning thing, but i wanted to use two round ports to minimize port noise. So if it says for example 30 in long for a 4 in. pvc, then how long would it be if i wanted to use 2 4" PVC's? Also, is it worth it to spend like $12 each on those flared ports, or will it work alright if i just sand the edges on some pvc? Thanks for any help.