Ahh, yea I was just looking at the datasheet's and knew that mms was moving mass lol... I'm quite a newbie.
However, I'm not going with a second 10 because a single 15 is still louder and will actually use up less of my trunk, while being about the same price as buying another 10. Plus, I like the clean look of a single woofer and especially the look of a 15 //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif My 10" box needs rebuilding anyway because I'm getting too much port noise, so I'd go through as much, if not more hassle with another 10.
You can always buy my setup!