Mach 5 ixl 18" experts and everyone else. lol

So here it is.
At the moment I have 2 of these in their own ported enclosure of roughly 12cu ft tuned to 14 hz.
After moving the subs to the harmon recommendation haflway on the side walls facing each other i seem to finally have the impact I was looking for originally.
The problem is they are way too big and interfere too much.

My idea is to go sealed and make them as shallow as possible. width and height don't have any limitations.
Here is a picture where you can see how much they intrude in the room.

So what I'm asking is what is the shallowest I can make the sealed box, and what is the optimum size I am looking at.

I guess I will eventually need a BFD or something similar, but that will come later.

Thanks
Mike

For the price I paid they are amazing. Granted, I can't compare them to anything else but the 12"jbl gt in my car. But, they seem very well.

Arthur. How low can they go in sealed alignment.

Sound q they seem to be pretty good for music and awesome for home theater.
Output they are each running off of a channel on my ep2500.

So, if I'm using them for ht use more than music do I stay ported and just build slimmer cabinets.
I'm liking the idea of the smaller sealed cabinets.

lmao.
I didn't even know that was on until I took the picture. When I'm on the computer the tv is on just for backround noise.

Mike