Honestly my friend. I can understand the theory behind it. It is cause of perceived reality. Of course we are taught more is louder. But honestly for example. 1 15 ported done right can definately be louder than 2 15's sealed. maybe even as loud as 4 15's sealed. also depends which subs. I could take a audioque HD3c 12" and make it as loud as 6 pyramid 15's lol. It is all about install and box designs. REally mostly the box. I have a type R 12 with about 500 watts in a custom 6th order BP I designed. it is LOUD. you can hear the car rattling like crazy. dash seats everything. blurs your vision almost as much as when I had 1800 watts and 3 15's in my wall in my taurus and this is in my trunk in my zx2. INSTALL INSTALL . it is definately louder than my 3 15's I had in my trunk in my buick back in the day with 1600 watts and this is ONE 12. install install install can I say it a few mores. install equipment install install install install