I'm in the process of extending my dust collection to a Powermatic dual drum sander that has 2 - 4" exhaust ports. I plan to come off of an 8" main that is fairly close to the Oneida venturi type dust collector with either a 6" or 5" branch, then to a wye fitting that has 2 - 4" ports. A 6" branch would obviously carry more volume than the 2 - 4" ports or 5" branch but with less velocity. Would the 5" branch be better considering the greater velocity?