15" si mag sealed or 12" mag ported at 30 hz

[DFW40 10+ year member]

I would go with the 12 ported. Isn't 2 cubes a little small for the 15 inch mag sealed. I had mine around 2.9 and it sounded great but I would be a little afraid to go as small as 2 cubes for the 15 because you might lose some of the low low end.