HAHAHAH, just buy some XPLODS, i bought 3 XPLODS the othe day from walmart $99 a piece for each 12", $99!! is a great unfrickin-believable price. So i figured i would buy 3 of them, in a Jensen bandpass box. They are running like 3000W max, and that is unfreakin-believable for $99 each. They hit soo hard off of my 1000W Xplod amp, I only have 1000W for 3000W subs but hey, they are unbelievable..So for all u guys who spend all that money on alpine and JL Audio, just go down to walmart and pick up some Xplods, ull be happy u did....XPLOD FOR LIFE!!!!!!, I traded my type-x 12" for 3 xplod 12's and boy am i happy!!!!
in a ported enclosure yes the 2 12's would be louder due to surface area. In ported enclosure'e the sub soesnt rely on xmax but on motor strength. In a sealed enclosure it would be tough, although the sub with 40mm of xmax might be able to move a ton of air the 2-12's have double the surface area yielding 3db's for surface area, and 3db's for double power(hypothetical) so will the 40mm of xmax make up the added 6db's or 9db's to make a audible difference between the two I highly doubt it.
My 3 12" Xplods hit 165 DB, the other day, no joke man, not even my rockford stage 1 12's could do that...so you can go eat some JL or apline and poopy outta XPLOD
If that was soo much true then my three Fosgate PII's would put out more than my One RE sx15, lol, they don't not even close! Xmas really comes into play on the lower notes where peak excursion is really seen. Just remember, at peak a sub in a ported enclosure loses excursion so that is where BL and surface area would come into play, not to mention power. JMHO...Polo..