bar none in a cavalier you will be louder with a wall. 4 15s will fit. at least in my 01 they will. its 52 across at the bottom straight up to about 28 inches and then tapers in to 40 ish can fit four very easily if you build it in pieces and inside the car. once I get moved into my house i will have 4 DD 9515s powered by 4 orion 2500ds in mine.