6" aeroport

I'm about to start building an enclosure for a 15" Fi Q d2 and I'm using a full length 6" (17-18" long) Aero port kit from parts express. Which would work better? 3.0 net@33hz or 4.0 net @29hz, or somewhere in between? It will be run off a Sundown saz-1500v2 @ 1ohm. Half of the music I listen to...