I have an re sx15d4 in a box that is 2.9 cu ft gross w/2 3" wide 10" long aero ports. I will be running an saz1500d @2 ohms into this sub. I want the best sq I can get from this sub. So I'm looking for box recommendations. Right now I'm looking at building a 4.2 cu ft box tuned to 34 hertz with a slot port facing the back of my jeep and the sub firing up. I used the box calculator to design the box.

that sounds about right i done 2 15s in 4.5 @35 a piece and they got down pretty good they dont have the best sq but its not horrible either they just have some serious output SX's can get damn loud

Here's the slot port box t i designed on RE's website., sub firing up, port firing back. Width 30, height 18.5, depth 21. Port height 17, port width 3.75, port length 1 16.5, port length 2 4, sq port area 63.75, box volume 4.467 cu ft, tuned frequency 33.89. If this sounds good i'll get to building.

I had my sx15 in 3.5 cu ft after all displacements tuned to 33hz. Used 2 4" aeroports on mine tho. I think a slightly larger box would have enhanced the low end, but the sub sounded very good when listening to rock and the like. Rap it just tore down on, I would've just liked a bit more lows, but i couldnt fit any bigger box, unless i build it in the trunk.