@splfanatic...i think he actually wants clarity as well. which only subs like SPLX, CVs, type Rs and MTX will provide. something 308 will always lack in...
but if talking purely about loudness, than 10-20 difference nahi ho ga if he uses only one sub...
@aqgmbest..i have seen a city literally break apart with just two 308s...so you might be doing something wrong. maybe sell ur amp, and install a pair of soundstream SPLX...phir maza aae ga
i will still say, try to get a pair of CVs, or type Rs - both 12"s...put them in a proper box. they will be well balanced for ur x11d. theek thaak loud ho ga setup aap ka.
or a pair of MTX THUNDER 6000 (T612s-22)...kharcha tou phir bhai kerna parae ga if you want something better than CVs and type Rs and 308s..