Two Obsidian 15's/trailblazer box help

[greezychef]

You can also notch the box at the bottom and get some more air space if you want. I have two DC level 5 15s in mine. The 4 3100s in the back and between the box and back seat is 2 dc 5ks and a 175.4.

That's beautiful.

[Terra Rysing]

Nice curves Kalilac619.

So I have been on Win ISD and I am doing a 7 cube box net and a 14.5"X4" port tuned to 31hz(I am using roughly 60 square inches of port for the pair based on the recommendation from obsidian of a 6" round port per driver) and I am having a high vent Mach of 0.27. The larger of the port I do the more it goes down.

I want to build it to obsidian recommendations but that can't be right.