Yes just make sure the edges are rounded and you'll be fine. Port vel is the speed of air in a port, usually expressed in ms(milliseconds) and varies with power and frequency, in other words a 100 watt amplifier will cause less port velocity than a 500 watt amplifier. The goal i like to shoot for is to stay under 23ms when the sub is placed in a trunk firing backward, and under 17 ms when placed in a hatchback or suv. The higher the port velocity you have the more of a chance you will hear "port noise" or the "chuffing sound" associated with a high port velocity. The more area you have for the port the less port velocity you will have, but the port will have to be longer to keep the same tuning.