You can use pvc, but the flare can still be on the outside if you use an aeroport. The flares come with holes for screws so you can screw them right into the wood. All you need to do is cut a hole big enough to get the port tube through and you'll mount the one side of the flare on the inside of the box so it is secure and the other side with the other flare on it on the outside. Trust me the flares help, but if you don't want to use them that's your call. I can't say how much louder they will be, but I'm sure it's enough to make a difference.