true, while the 12's do have slightly less, I should have proof read my earlier post, the dual 12's will have .0129 Sd versus the single 18 at .1426, but the eff of the 12" is 86.6 versus the 18's 90.27, so slight advantage to the 18", and Xmax on the 12's are 13.20 verus the EXmax of the 18" at 24.48, and with proper power (in previous post) the 18 will have the advantage over the dual 12's. Not to mention, with max power, say 5000 watts, the 12's will be maxed, as recommended ported power range is or around 1000 watts.
But to each their own which would be louder, as it would then become install dependant. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif