I have not picked a sub . I like the jl 13.5, but I dont know if I should tell you I want sound quality because is that possible with four? I want it but can I get it? So Ive thought about 2 10s and 2 12s for more response? Any link to the org thread? I searched and was not sucessful. I can't find boxes to buy either so I assume at this point this is all custom. I was thinking about trying RF shallows and just go from there to see whats possible as I dont find many setups like this in searching the web. Anyone know of some good audio forums that may have experience in this? My searching for a livly out of the box audio forum has come up dry also. Id just hate to know I spent 2500 on subs when i could of got the same result with p3s or something.
You need to be honest with yourself. 4 of any sub is for nothing more than volume. A SQ based system would use no more than two and preferably one.
Neither is wrong...just make sure you build what you really want.
There's not much space back there either. My enclosure is 3/4" void free Baltic birch and we managed an honest 1.25ft^3 sealed for a single Illusion Audio Carbon C12....which is hands down the best "shallow" sub on the market. It's more like a full size sub it just uses an inverted motor structure so it's only a few inches deep.
Anyway...you might find 1.5ft^3 but not much more. You're gonna be hard pressed to find four decent subs that will work in a space that small. Two subs in the right size enclosure will outperform four in a small enclosure all day long.
Car audio is a science....not just cramming in whatever will fit.