It is so far from a one word answer it is not funny. There are way too many unknowns to give an exact answer. Both are high output woofers, but so much is dependant on the enclosure. The pair of 15's should naturally by louder due to cone surface, but there are too many other factors to know for sure. At SSA we care about the details and not mindless inexperienced answers. So let's work on more info to help going in the right direction. In the end the answer will not be known until tested in your install. ok details. amp- sundown 3500d electrical- big 3, 3800 hc kinetik, truck- colorado box- dd 4.25 cuft tuned at 32 fi- 6 cuft tuned at 32 anything else needed? Fi. more cone area
