Wait a sec.... posted by Twainsville on February 12, 2007 at 01:32 AM
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When i calculated it out i got each runner being 3.013sqin, or 2.77" in dia. but only 1 runner (2 valves) are in use at any given time... There for the intake piping (and end tanks of the plenum) would need to be 2 7/8" (Or 3"). Makes sense now.