if you are glassing a box you will have plenty of room for rear speakers. 1 managed to get almost 1 cube per sub glassing and down firing 2 jl audio 8w7. while still being able to put the seats back and reclined. i have kenwood speakers at all four corners they suck the plastic grill surrounds came of them when i took them out to dynamat. the excelons blow. i will never buy another kenwood product. I left about 4 inches for the rear speakers to use.