Personally, I think that two 3" ports would look better just as a design, and plus the 3.5" hole saw is cheaper than a 4.5", haha. But is there an actual reason why I should stick with 1 4" as opposed to two 3" ports? I know the two 3" ports will have a tad more port area, but thats about it. Somebody please shine some light for me. Thanks for all the responses.