psssssssssst little hint:
i work for Fi.
You would have been much better off going with another woofer. I do not want to condone using an IB woofer in an enclosure. Nor do I want people to think that they can do it and expect good results. That's why we have the other lines specifically designed for the car audio scenario. This is the exact polar opposite of what I want people to think they can do with the speakers.
That sub is made for a house, or an IB install for a car. That's it. That is what it is optimized for.
Edit: Will it work in a car in a box? Sure! Will it work free air? Sure! Will it work if you put a hole in the roof of the car? Sure! Will it work in a sealed box that the motor sits on the back of it? Sure!
Is it optimal? No...not in any way, shape, or form. Is it optimal. You can buy a Lamborghini and take it and stick it in a mud hole. It's not designed for it, but if you've got enough money to do it...then you assuredly can.
There's the difference.
Regards,