I am doing a wall in my zx2 and I am limited to about 10-10.5 cubes after all displacements. I was wanting to go two 18's. All of them really require a really large air space. I can put the subs in winISD in that box and it peaks at like 60 hz.Which would be fine if it was loud through 40. but it really isn't The BTL is the closest . It peaks around 55 and still strong through about 44hz. Played with a few different tunings same results. Wonder if changing to a flatwound coil and copper coils makes any difference or if I can have a different set of spiders on them to make them peak near 48-50ish in the box I can do. Again 55 peak is okay as long as I am strong through 40 and can play to 35 at an ok volume at least. I know when you change anything on a sub it pretty well changes the way the sub plays . But I want to know which specific options I should select to get this to play lower. thanks for any help. If I can't get it to work then I will have to go with 4 12's. but I really wanted the ahhhh factor of 18.s this is a totally daily setup up, no comps. Also to what degree can you play with this... Like I would prefer to use the BL's and wonder if I could get them down there but right now they are graphing WAY high in that box. any help is greatly apprciated. I apologize about the "long winded" post